Upgrade React and related packages to 0.12.1

Remove @jsx pragmas (not necessary anymore) and use `render` in lieu of
renderComponent (which is being deprecated).

fixes #207
Update mocha runner for no JSX pragma
Treat underscores as characters
use arguments.length
Merge pull request #298 from hammerlab/complete-underscore

Treat underscores as characters
Address CR
Merge pull request #289 from hammerlab/issue-207-update-to-react-0-12

Upgrade React and related packages to 0.12.1
Test for ExaminePage, fix two bugs it found.
code review