A first pass at Computer Science exercises. Provides one exercise as a demonstration of what's possible.
Merge branch 'master' of https://github.com/jeresig/khan-exercises into cs-exercises
Update the URL in the CS utility file.
Program didn't need to be inside of a variable, was causing errors.
Fix formatting of wide CS exercises on tutorial pages.
Make sure that all whitespace is removed when doing a csPass exercise.
Use the znd-cs-exercises server if we're just doing HTML-file based testing.
Add in two new drawing exercises. Fix a minor width issue with the exercise display.
Fix issues mentioned by @beneater.
Implement showGuess which should make the timeline work. Thanks @beneater for the tip.
Add in a simple instruction for those encountering a csPass type exercise.
Update khan-site.css

Test plan: Load an exercise in local mode, note that it looks reasonable and
there's no longer a 404 when fetching the logo

Auditors: alpert
Fix issues with timeline playback of CS exercises. Required rewriting how events were handled as timeline exercises are built differently from normal exercises.
Pass along the origin to the embed so it can communicate back easily.
Switch to using all properties instead of just the new options.
Fix #35037

Test plan: Locally test the problem in the issue and the next problem (where
the parabola opens up)

Auditors: stephanie
Rewrite absolute_value_equations to not use multiple choice

Summary: CCing Emily since you might appreciate the interesting answer type hack

Test Plan: Tested locally

Reviewers: stephanie

Reviewed By: stephanie

CC: emily

Differential Revision: http://phabricator.khanacademy.org/D958
Realign linear_equations exercises to tutorial

Summary:
one_step_equations is now only a+x=b
linear_equations_1 is now only ax=b and x/a=b

Test Plan: Tested locally

Reviewers: stephanie

Reviewed By: stephanie

Differential Revision: http://phabricator.khanacademy.org/D911
Fix #35071 minor error in hint

Test plan: Tested locally

Auditors: stephanie
Fix wording for tax problems