Make django use_tz

PREVIEW_LMS_BASE must now be set (default value does not work for both edge and edx). Make this work locally as well.
https://edx.lighthouseapp.com/projects/102637/tickets/331

Start linting envs files, add task to only pylint errors, and move pylintrc file to the correct location

#324

acceptance tests.

Use setup.cfg to set up default settings when running nose tests. Enable
the rednose library to color test output.

use django caching to hold computed metadata inheritence. Also invalidate the cache entries on writes (insert, updates)

Move modulestore unique naming in tests from the settings.py file into the ModuleStoreTestCase class.

Sketchy adding of test dbs to the cms test.py config file -- these are required for the Student (shared django app) tests to run

Add tests for the edit page for the toy course, and make sure that exporting to github sets up the git repo properly

* NOTE: successfully running the tests depends on an updated version of
  django-pipeline, which fixes a unicode bug (https://github.com/MITx/django-pipeline/commit/efaba4ac63bc635da6a728603e87e14758541ec7)

Config changes:
* Use separate db for the cms
* Run collectstatic before running tests--needed to get everything in the right place for loading pages
* fix some paths related to this
* Turn off JS compressor for CMS
* add empty test_root/uploads dir

Code changes:
* Add cms tests to check that home page and signup pages load
* Add cms account creation test
* Make github sync tests clean out repo dirs before running.

Acknowledge the fact that right now keystore is really just a module store. If we need a keystore that returns other objects, we can reexctract the base class into it's own module again