Make TinyMCE more tolerant about HTML elements

STUD-1565
fixes templating error (LMS-2560)
Remove verify_html as it isn't supported in TinyMCE 4
Merge pull request #3442 from edx/adam/fix-template-error

fixes templating error (LMS-2560)
Merge pull request #3437 from edx/andya/rc-fix-tinymce

Make TinyMCE more tolerant about HTML elements
Add support for raw HTML editor.

STUD-1562
adjust codemirror window on raw HTML editor
UI String  Updates for Raw HTML Editor Change

Modified the Raw HTML template text and the help string for the Editor
setting.
Tests for raw editor and minor wording changes.
Merge pull request #3449 from edx/hotfix/2014-04-24

Hotfix/2014 04 24 Raw HTML Editor for Studio
Fixed transform_url function in WikiAccessMiddleware.

In the current implementation if the path prefix contains the
wiki_path value it gets deleted. For example if the prefix is
'/courses/edx/math101/2014' and wiki_path is '101/' the final
prefix becomes '/courses/edx/math2014'.

LMS-2556
Fix i18n of video transcript
Merge pull request #3476 from edx/usman/lms2556-wiki-urls

Fixed transform_url function in WikiAccessMiddleware.
Merge pull request #3494 from edx/sarina/fix-video-i18n

Fix i18n of video transcript
Merge branch 'release'

Conflicts:
	CHANGELOG.rst
Updated note about accessing wiki after hiding page

doc-310
Merge pull request #3499 from edx/markhoeber/documentation/doc-310

Updated note about accessing wiki after hiding page
Fixed all links in release notes

moved links to links.rst

Doc-327
Merge pull request #3496 from edx/markhoeber/documentation/doc-327

Fixed all links in release notes
Convert lettuce video tests specifically using youtube stub