Fix bug with fake_sympy_function and negatives
Refactor result sets, add URL to eval single card
Basic AJAX evaluation
AJAX evaluation

Changes:

- Switched from Django's dev static file hosting to App Engine's
  static hosting
- Refactored backend
- AJAX loading of card results
- Loading animation
Eliminate redundant data transfer
Trim unnecessary CSS
Handle errors in AJAX evaluation
Result cards can accept parameters
Fix bugs with evaluation

- Return original input, not evaluated input, so that input that
  results in long strings (e.g. 1006!) doesn't give an HTTP 414
  error (URL too long)
- Properly escape expressions in HTML
Fix issue with fake functions and parameters
Properly convert input in card eval
Fix issue with title formatting
Fix simplification card
Switch to URL parameters
Refactor JS
Further refactor JavaScript
Fix simplification formatting
Pannable plots (x only)
Plot panning (in-progress)
Cap graph y values at +/- 1e8 to avoid browser crashes