Start down path of new build system:

- Move tests to karma test runner and mocha framework, also adding chai assertions
- Add gulp tasks for testing, watching, concatting and compressing
- Update travis file to use new build system
- Remove jstestDriver stuff
- Reorganize a bit so that it's easier to see what's going on
- Create a dist folder to hold the output of builds (should probably look at having a bower branch/repository where these are held, instead of master)

I'm pretty sure we don't want to push this to master, but that's where this was diffed against.
dygraph-dev was pretty fragile due to the ordering of the files. The build system now creates a dygraph-combined.dev.js that puts everything in the right order, maintains that order in one place and includes the dygraph-options file that is only for dev.