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.
Switching to smaller sample data.
Added missing karma-sinon
Refactoring to use karma fixtures.

- Chrome hangs for some reasons on the audio file, some work needs to be done to check the cleanup between each test is properly done.
- using mp3 as it's smaller than the wav.
Migrating assertion framework

- mocha deals better with asynchronous tests
- fixtures helper
- creating the audio element once, recreating the canvas fixtures every time
Migrating tests to mocha+chai

And it works surprisingly well! (and faster)
Merge pull request #13 from bbcrd/feature-travis-mocha

Migrating to Mocha+Chai for tests
Merge pull request #3 from bbcrd/feature-travis

[WIP] Adding TravisCI + Saucelabs