When issuing `delete` commands that would require three or more
individual deletes, check whether the cluster supports bulk deletes
and use that if it's available.

Additionally, a new option is added to the `delete` command:

  * --prefix <prefix>

    Delete all objects that start with <prefix>. This is similar to the
    --prefix option for the `list` command.

Example:

$ swift delete c --prefix obj_prefix/

    ...will delete from container "c" all objects whose name begins with
    "obj_prefix/", such as "obj_prefix/foo" and "obj_prefix/bar".

Change-Id: I6b9504848d6ef562cf4f570bbcd17db4e3da8264

When we introduced LengthWrapper, we neglected to make it resettable. As
a result, upload failures result in errors like:

    put_object(...) failure and no ability to reset contents for reupload.

Now, LengthWrappers will be resettable if their _readable has seek/tell.

Related-Change: I6c8bc1366dfb591a26d934a30cd21c9e6b9a04ce
Change-Id: I21f43f06e8c78b24d1fc081efedf2687942e042f

Currently, if you attempt to stream an upload from an iterator, as in

    def data():
        yield 'foo'
        yield ''
        yield 'bar'
    conn.put_object('c', 'o', data())

... requests will faithfully emit a zero-length chunk, ending the
transfer. Swift will then close the connection, possibly (if Connection:
keep-alive was set) after attempting to parse the next chunk as a new
request.

Now, Swift will receive all of the bytes from the iterable, and any
zero-byte chunks will be ignored.

This will be fixed in requests [1], but not until an eventual 3.0.0
release.

[1] https://github.com/kennethreitz/requests/pull/2631

Change-Id: I19579ed7a0181ac3f488433e7c1839f7f7a040b8

 * Always use testtools.TestCase, since we're relying on testtools
 * Always use mock (as opposed to unittest.mock) since we're relying on
   mock
 * Add note about when a missing logging handler was added
 * Stop %-formatting the giant usage string that doesn't actually need
   any formatting
 * Prefer assertIs, assertIn, assertIsInstance over assertTrue
 * Use else-self.fail instead of sentinel values
 * Check resp.get('error') is None before checking resp['success'] is
   True, so test failures actually tell you something useful
 * Tighten some isinstance assertions
 * Import MockHttpTest from correct location
 * Only populate clean_os_environ once
 * Use setUp for setup, not __init__
 * Replace assertIn(key, dict) and assertEqual(foo, dict[key]) with
   assertEqual(foo, dict.get(key)) when key is a literal and foo is not
   None
 * Use mock.patch.object instead of manually patching for tests
 * Use six.binary_type instead of type(''.encode('utf-8'))
 * Stop shadowing builtin bytes
 * Reclaim some margin
 * Stop checking the return-type of encode_utf8; we already know it's
   bytes

Change-Id: I2138ea553378ce88810b7353147c8645a8f8c90e

This commit adds the utils module to those for which Sphinx
automatically generates documentation from docstrings. (Many of the
functions here may be of little interest to users, but
`generate_temp_url`, at least, definitely deserves to be in the
documentation; in this way, this commit can be seen as a spiritual
companion to ca70dd9e.)

Also, a few markup errors and perceived infelicities in existing
docstrings are amended.

Change-Id: I8c66a23cb359d7dd9302a16459fad9825fedb690

The `tempurl` subcommand's second positional argument is called
`seconds` and has heretofore interpreted as the number of seconds for
which the tempURL should be valid, counting from the moment of running
the command. This is indeed a common, if not the most common,
use-case. But some users, occasionally, might want to generate a tempURL
that expires at some particular ("absolute") time, rather than a
particular amount of time relative to the moment of happening to run the
command. (One might make an analogy to the way in which Swift's expiring
object support supports an `X-Delete-At` header in addition to
`X-Delete-After`—and it's the former that must be regarded as
ontologically prior.) Thus, this commit adds an `--absolute` optional
argument to the `tempurl` subcommand; if present, the `seconds` argument
will be interpreted as a Unix timestamp of when the tempURL should be
expire, rather than a duration for which the tempURL should be valid
starting from "now".

Change-Id: If9ded96f2799800958d5063127f3de812f50ef06

This patch adds exception logging to the swift service API. Each
operation that results in failure of any operation will now log
the exception as well as report a timestamp and full stack trace
in the results returned by the service API calls.

Change-Id: I7336b28354e7740ea7d048bdf355e3c1a1b4436c

In addition to removing an unnecessary dependency, this closes another
hole that was allowing raw bytes to appear in user-facing messages.

Change-Id: Ia0b76426a38e5a5c368c4c7e7ba2aef286758aca

With MD5Sum checking being added, a concern was brought up that It was
a change with no possibility of reverting to the old behaviour.
This change adds the flag '--ignore-checksum' to the upload subcommand
allowing the checks to be turned off.

Changed occurrences of the magic string for a null md5 to use a descriptive
constant instead.

Updated Error messages generated when validation fails. They should now be more descriptive
and not output a literal newline sequence.

Change-Id: Id1756cbb6700bb7e38f0ee0e75bc535e37f777ed