Revert to older version of TinyMCE.

We had trouble with Cloudfront/hashed files and need more time
to investigate.
This reverts commit e8f53ac9dc6d8a1d9928787635c7c5f7e409a9ec.
Merge pull request #3067 from edx/christina/revert_tinymce

Revert to older version of TinyMCE.
Merge pull request #3070 from edx/adam/middleware

wiki middleware fix (LMS-2461)
Concept added to Studio advanced components
Skip collectstatic when falling through from rake assets:coffee
Merge pull request #3082 from edx/db/rake-coffee-to-paver-skip-collect

Skip collectstatic when falling through from rake assets:coffee
Update testing.md file.

How to run Python tests for stub servers.
Merge branch 'release'
Fix failing tender.
Merge pull request #3092 from edx/valera/fix_tender

Fix failing tender.
Make YouTube mocked server serve YouTube API

1.) Making YouTube mock server serve YouTube API.
2.) Adding ability to block YouTube API from YouTube mock server.
3.) Adding acceptance tests that check YouTube mock server for availability of YouTube API, and for it's ability to block YouTube API.

Part of BLD-939.
Addressing comments.
Addressing comments.