Updated video compression specs

Fixes DOC-1301. @srpearce , @mhoeber , @catong I’d like to publish this
correction as soon as possible.
Merge pull request #33 from edx/ahodges/compression_specs

Updated video compression specs. Fixes DOC-1301
OLX For Studio Doc
Merge pull request #29 from edx/markhoeber-doc1258

OLX Studio Example
Update info about superscripts and subscripts
Merge pull request #36 from edx/sylvia/docs/anant-subscripts

Update info about superscripts and subscripts
Fix html sample and note that full tags needed
Merge pull request #37 from edx/carol/docs/DOC-1055

Fix html sample and note that full tags needed
Update when students are assigned to groups for content experiments
Merge pull request #34 from edx/ahodges/randomize_AB

Clarify when randomization happens for researchers: Fixes DOC-1182
Fix typo: arithmetric -> arithmetical
Merge pull request #40 from edx/sylvia/docs/math_formatting_typo

Fix typo: arithmetric -> arithmetical
Add weekly highlights template. Move Bulk Email to own section from Course Launch Activities
Merge pull request #38 from edx/carol/docs/DOC-1127

Carol/docs/doc 1127
Put December entries in new month in change log
RN 12/3/2014
Merge pull request #41 from edx/markhoeber-doc1254

First draft RN 12/3/2014
Add wiki info to student-facing documentation