Unrevert i18n stuff only in the i18n branch for now
i18n-ize some exercises

Summary:
i18n-ize inscribed angles exercises, indepdent probability, and identifying
points 1

Test Plan: View those exercises, notice that they're not horribly broken

Reviewers: eater, emily

Reviewed By: eater

CC: alpert

Differential Revision: http://phabricator.khanacademy.org/D2063
Create a rational expression object
Fix formatting of expression with coefficients of 0 or 1
Make a start of +/- rat expr 1.5
Add numerator and question
Improve dealing with 0 in terms
Add functions for finding the GCD
Use KhanUtil where required
Create more sensible, less random questions
Find GCD of solution to check for simplification
Multiply question by value for more interesting questions
Create multiplying_fractions_by_integers

Create multiplying_fractions_by_integers from multiplying_fractions
update multiplying fractions by integers
fix a few bugs
whoops, forgot to change that back
close p and code tags on line 32
fix bug with GCD
hints don't show extra step
Fix factor code