Also add more tests.

This addresses:

https://github.com/PyCQA/pyflakes/issues/149#issuecomment-305881232

Previously, only files ending with `*.py` would be detected as Python
files while recursing a directory.

This closes #149.

I previously noticed the badge going awry. This explains it.

This also adds the latest version of Python.

The `setuptools` on Travis CI no longer supports Python 3.2:

https://github.com/pypa/setuptools/commit/b47fe15b9039a165589353a1a43f6dfe3bbe3a8e
https://travis-ci.org/myint/scspell/jobs/235721220#L146

Forgot to push the commit that increments to 1.5.0 when I made the
release, and some changes have been made since then :(

* Don't test against file perms when running as root

test_permissionDenied tests file modes by creating a temporary file, then sets the mode to 0000 and attempts to process it and see if and permission denied error is generated.  This never happens when the unit tests are run as root since it can open files regardless of file permissions.

* Fix up UID skip in tests for Windows

Even though variable annotations in function scope aren't evaluated at
runtime it's still useful for static analysis tools to process them and
catch some issues (and not report some things that aren't issues).

Let's take the following code:

     from typing import Any

     def fun():
          a: Any

Previously pyflakes would report Any to be unused:

     test.py:1: 'typing.Any' imported but unused

With this patch it's no longer the case.

Use the get-pip script to bootstrap pip and setuptools to pinned
versions for Python 3.2 compatibility.

PyPy3's latest Windows version only supports Python 3.2, so while Python
3.2 is EOL upstream, we're still testing against it and need to be able
to install our tooling (including pip and setuptools).