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.
This isn't really the most general way to have categories. It would be better if `list_of_quicktests.json` was loaded and the dropdown was generated from there. Use
```javascript
d3.json("/quicktests/list_of_quicktests.json", function(error, json) {
  ...
}
```