Cleanup module dependencies w/ using more requirejs for deps

Test Plan:
- Load app, make sure it still works
- Run tests
Move third party deps to using bower
Fix tests from the addition of exercises
Remove model parameter from onProgress callback since it is unused
Force onProgress to be called in every invocation of downloadContent
Show individual download progress
Use render instead of renderComponent

Test Plan:
- None
Kill some react warnings

Mostly based on using key instead of position

Test Plan:
- None
Cleanup some logging
Fix React warning for passing array expecting object

Test Plan:
- None
Resolve katex reference for perseus

Test Plan:
- Load an exercise involving katex (number grid 1st one)
Merge pull request #61 from max-li/download_progress

Show current download progress
Add in KAS dependency

Test Plan:
- None
Allow cancellation of individual downloads
Allow cancellation of individual downloads
Add a cancel download button to the status bar