Feature/ichuang/update symmath server

Merge pull request #1227 from MITx/feature/ichuang/fix-capa-contextualize-text-for-option-response-and-mc

fix capa to add contextualize_text for optionresponse and multiplechoice

Fix parent lookups when the same named tag exists in multiple courses

The parent trees are built on a per-course basis (so it'll throw ItemNotFoundError
if an item exists in a different course from the one you're asking after. NoPathToItem
can still happen with MongoDB backed courseware. They store things like the info page
as HTML snippets which are orphaned from other content.

Clarify the syntax of the rake fasttest command

Clarify that you need to start up the mongo daemon

Fix typos in job and faq pages

Signed-off-by: Carlos Andrés Rocha <rocha@edx.org>

Add new tab/window behavior to media kit

media kit - added in new tab/window behavior for download links, revised edX name styling on homepage cta, and provided more context on logo download text

Fix error in one of the media kit assets URLs

Minor style changes to home page and media kit page

[Finishes #41872203]

[#41872203]

Add media kit page

[# 41872203]

Vik/modify open ended

Add splinter to test-requirements.txt

Merge the lettuce acceptance test framework to master