Tox has already been removed from `make test` and is no longer recommended
for testing in the contributing guide. Additionally, the extra tests it runs
(checking the spelling of documentation, etc) are of no value to end users.
As things are currently set us, tox is only used on the Travis CI server.
Given the above, there is no reason to include it in the release tarball.
Closes #808.

All file-based tests are now defined as unittest test cases via a
metaclass which walks a directory and builds a unittest for each pair
of test files.

To run the tests just run `python -m unittest discover tests`. Or use
tox as the tox config has been updated to run the new tests and all nose
specific code has been removed.

The test generator tools have been removed as well. If any changes or
additions need to be made to tests, they should be implemented using
the new framework rather than with the file-based tests. Eventually,
only the PHP and pl tests should remain as file-based tests.

Fixes #621.

Use console_scripts entry_point instead of manually built script.