Adds a popover feature showing additional information for each build in travis_builds monitor.

Also fixes issue which caused proxy server to exit whenever it received a bad response. See server/requestProxy.

Some other notes:

* I modified .gitignore. I noticed that index.html was in that list, and I couldn't understand why. Also, I needed to make modifications to index.html, so this was necessary.
* I formatted the "duration" value of the build into human-readable output. I assumed that the value was in seconds. I noticed that the finish time minus the start time seems to always be much shorter than the duration though. Not sure if that indicates a problem somewhere.