Bower compatibility

Fixes #2

* Remove vendor
* gitignore bower installed dependencies
* Add bower.json
* bower manages jQuery dependency
* bower manages QUnit development dependency
* npm manages Sinon.JS development dependency
* Tests reference npm and bower installed dependencies
* On Travis CI, bower install dependencies
* Run tests with npm installed phantomjs
* README updates:
  * Show how to run tests with npm installed phantomjs
  * Note dependencies are managed by npm and bower