Tests & CI!

Before I went deep into API work (e.g. JSONP, CORS), I wanted to give us a proper test suite.

- [x] UI tests (e.g. homepage, view page)
- [x] API tests
- [x] URL fixtures for future tests

With that, hooked us up to Travis CI (fixes #12). Example build:

https://travis-ci.org/zoomhub/zoomhub/builds/38115214

Also in the process, updated our various dev dependencies. Until we check them in (issue #47), be sure to run `npm update` locally before expecting `npm test` to pass.

Edit: also fixes #31 (thanks Melinda).