Extends the Programs ConfigurationModel, cleans up Programs-related utilities and corresponding tests, and corrects caching. Uses the Programs API to list programs within Studio. ECOM-2769.

Please note that this is a squshed commit and the work of:
Symbolist, macdiesel, nedbat, doctoryes, muzaffaryousaf and muhammad-ammar

This includes:
* Ability to specify number of processes to run bok-choy tests in
* A forked nose commit to get the multiprocess plugin's logging to work
* A different plugin (xunitmp) must be used for pulling together xunit results

This works by:
* Starting the various servers that are needed for the acceptance test environment
* Running the tests themselves in multiprocess mode

* Fix paver violations to stablize edx-lint update
* Parens, Line2Long
* Fix missing docstrings
* Fix PEP8 issues
* Address PR feedback (thanks @nedbat!)

On my devstack, the old line takes about 5.5 seconds, the new line takes
about 1.3 seconds.

For background:
http://nedbatchelder.com/blog/201505/be_careful_deleting_files_around_git.html

I want to make clear that these tests rely on XBlocks in other repos,
and that ideally in time we would move these tests into the XBlock repo.

The old line:

    from path import path

produced pylint errors because of the baroque way that path.py defined
"path".  We tried to get them to change how they defined it, but they
deleted the name instead: https://github.com/jaraco/path.py/issues/102

(Jason then changed his mind, but this is a better way to use path.py,
it avoids the pylint error at least.)

TNL-2465

This reverts commit 4312c0e7.

This would allow a user to set up and run servers, with an open prompt for killing
them. Likewise a user could open a different terminal session and run tests only.

How-to:
* At a terminal/ssh session, start bok-choy servers with
    `paver test_bokchoy --serversonly`
    (or, if you've already run collectstatic on your system:
    `paver test_bokchoy --serversonly --fasttest`)
* When the above is running, you can now open a separate terminal/ssh session
and run:
    `paver test_bokchoy -t my_tests --testsonly`

Keep in mind, the 'testsonly' flag does no setup. There is some minimal teardown; however,
such as clearing mongo and flushing the lms database. (Some tests have non-unique identifiers
and could not be run more than once.)

This reverts commit 52c4aaca.

If you have a branch named "remove-all-.pyc", the original code would
clobber it inside the .git directory, because branches become files with
the same name.  This prevents find from looking in .git, saving your
precious oddly named branches.

This allows developers to pass the `--pdb` flag to paver test commands,
and that flag will be proxied to the `nosetests` command. It's useful
for debugging purposes.

This reverts commit 747756a9.