Dropdowns!

Keywords: now a dropdown with all keywords included in options
Feature Branch: automatically populates based on our github branches

added 3 tests. select_bars.js has problems, no matter which side you drag a box on,the bars on the right side get highlighted.
All of these changes probably mean that you didn't update typescript to the latest version. Try running `git merge master && npm install && grunt`, and `plottable.js` should no longer have this strange diff.