Merge pull request #2445 from edx/sylvia/documentation/STUD-1145

Add documentation for "multiple choice and numerical input" problems
Removed LANGUAGE from devstack settings
Merge pull request #2442 from edx/giulio/fix-disabled-about-page-button

fixing layout/style of disabled register button
adding check back in
Merge pull request #2447 from edx/flowerhack/fix/update-language-settings

Removed LANGUAGE from devstack settings
Merge pull request #2441 from edx/dcs/info-remove-title

Removed extraneous title block that was replacing the breadcrumbs
Don't show course start date if it hasn't been set.
If neither start nor advertised_start has been changed from default
don't show the course start date.

This allows us to accept course registrations for courses whose start
date is yet TBD.
add unit test for speed_change_video event
Added missing import of sys to i18n/dummy.py
Removed unused make_dummy.py
Made dummy.py executable
Allow multiple client-side runtimes on a single page

Make XBlock client-side runtimes proper classes, so that handlerUrl can
be defined in a per-runtime way, and we can have multiple runtimes on a
single page.

[LMS-1630][LMS-1421][LMS-1517]
check for None so an empty string is valid for a password
adding DB_MIGRATION_ENGINE and fixing defaults
fixing syntax
Add "Protein Builder" to "Additional Tools"
Prepend theme template paths

Allow templates override.
Merge pull request #2444 from edx/markhoeber/documentation/LMS-2140

Add info to external graders chapter
Add ProteinBuilder.gif
Merge pull request #2450 from edx/will/fix-dummy-i18n-import

i18n/dummy.py cleanup
Rename of feature AUTH_USE_MIT_CERTIFICATES to AUTH_USE_CERTIFICATES across platform.
Caution! This is backwards incompatible
Merge pull request #2453 from edx/sylvia/documentation/BLD-759

Add "Protein Builder" to "Additional Tools"