Fix travis build errors

[mcalthrop]

Errors: https://travis-ci.org/mcalthrop/angular-spa-demo/builds/32481504

Travis can't find any of the browsers specified to run the unit tests.

Possible options:

• use phantomjs
• use Firefox (See http://karma-runner.github.io/0.12/plus/travis.html)
• use both

See also http://docs.travis-ci.com/user/gui-and-headless-browsers/

[mcalthrop]

Working Travis build. Woohoo!