Travis configuration

- updated tests to run on the new release of waveform-data
- experimenting with Firefox on Travis
Using bower install directly
Saucelabs testing setup
Building before testing sounds a good idea.
Enabling Travis caching
Declaring ruby dependencies
Switching to Ruby 2
Bumped `grunt-bower-install` to its regular version.

The original multi-task PR has been merged, and bugs fixed then.
Caching bundler too.
Trying with another version of Chrome as it keeps disconnecting on Windows.