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 #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
Merge pull request #35236 from xymostech/tax-wording

Fix wording for tax problems
Update README with basic info on using local mode

Test plan: Daily for the last year

Auditors: alpert
Fix #35686 fix typo

Test plan: Use a spell checker?

Auditors: stephanie
Fix #35616 Make cube root larger/legible

Test plan: Local mode

Auditors: alpert
Remove a couple (maybe even 3) pixels of whitespace

Test plan: squinted

Auditors: alpert
Add exercise: Logarithms 1.5

Summary:
Inspired by the comment:

> The exercises should include negative and fractional logarithms as well, e.g. log(8,2) = 1/3 and log(4,1/64) = -3.

Test Plan: ... looked at hints for all the different cases? Not sure what one writes in a test plan for new exercises.

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D979
Make-better the dividing complex numbers exercise

Summary: Now the answer is always an integer and the hints make more sense when dividing by a single term.

Test Plan: ...looked at the hints?

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D980
Equations should have equals signs

Test plan: tested locally

Auditors: stephanie
Move images around to match the directory structure in ka-stable.

Summary:
This should make it easier to keep images up-to-date between the two
repos.

Test Plan:
Once I have 'arc mail'-ed this off, I'll check that the images display
correctly for this revision in the two reading-pictograph exercises,
on sandcastle.

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D985
Fix a url to use urlBase, so it shows up in sandcastle.

Summary:
There are still some urls I can't fix up, since they're in static
html rather than javascript, but this is better, at least.

Test Plan:
Once I 'arc mail' this, I'll go to one_step_equation_intuition on
master and make sure it displays the images correctly.

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D984
Separate out imageBase from urlBase.

Summary:
urlBase is meant to point to the root of khan-exercises.  For images,
this isn't entirely appropriate, because khan-exercises just has a
copy of the 'canonical' version of the images (which live in the main
KA repo).  So imagesBase should be the same as urlBase only when the
canonical version of the images isn't available, and we have to use
the khan-exercises copy.  In cases where the canonical version *is*
available, we should default to using that.

I distinguish the cases where the canonical version is available or
not based on testMode.  More principled (but also slower) would be to do an actual ajax request
for an image, and see if '/images/face-smiley.png' is a 404, or we
have to use '/khan-exercises/images/face-smiley.png', and set
imageBase that way.  But this should work well enough.

Test Plan:
One I 'arc mail' this, I'll go to I'll go to
one_step_equation_intuition and reading-pictographs-1 on
sandcastle.khanacademy.org (for this phabricator revision) and make
sure they display the images correctly.  We'll also have to double
check that they also work correctly once we deploy this to the live
site.

Reviewers: eater

Differential Revision: http://phabricator.khanacademy.org/D986
Pass along the definition of imageBase, as needed.
Fix this: http://www.youtube.com/watch?v=RSCmw8GWdzU

Instead of the exercise being gamable as described in the video 75% of the time, make it 50%

Test plan: tested locally

Auditors: stephanie
Separate out imageBase from urlBase.

Summary:
urlBase is meant to point to the root of khan-exercises.  For images,
this isn't entirely appropriate, because khan-exercises just has a
copy of the 'canonical' version of the images (which live in the main
KA repo).  So imagesBase should be the same as urlBase only when the
canonical version of the images isn't available, and we have to use
the khan-exercises copy.  In cases where the canonical version *is*
available, we should default to using that.

I distinguish the cases where the canonical version is available or
not based on testMode.  More principled (but also slower) would be to do an actual ajax request
for an image, and see if '/images/face-smiley.png' is a 404, or we
have to use '/khan-exercises/images/face-smiley.png', and set
imageBase that way.  But this should work well enough.

Pass along the definition of imageBase, as needed.

Change imageBase to include the /images directory.

Test Plan:
One I 'arc mail' this, I'll go to I'll go to
one_step_equation_intuition and reading-pictographs-1 on
sandcastle.khanacademy.org (for this phabricator revision) and make
sure they display the images correctly.  We'll also have to double
check that they also work correctly once we deploy this to the live
site.

Reviewers: eater

Reviewed By: eater

Differential Revision: http://phabricator.khanacademy.org/D986