Update 'data' method and cleanup JS header.

Remove unnecessary header comment in JS source. 
Updated data method with 'videoLoadedFraction' property.
Update default volume in unit tests.

Seems as though the player persists the users preferred volume. 
Unit tests now validate against a volume that is determined upfront.
Fix for #38: 'cue' makes use of 'preferredQuality'
Fix for #39: getVideoEmbedCode -> videoEmbedCode
Fix for #37: playbackRate method and property

.tubeplayer('playbackRate')
.tubeplayer('playbackRate', 2)
.tubeplayer('data').availablePlaybackRates
Update readme for "playbackRate" method
Update unit tests.

Added HTML5TrialMode flag. 
Update tests to use predefined player volume.
Account for HTML5 trial in tests.
Fix seek test.
Fix quality test.
Added playbackRate test.
Added a test for 'data' method - ensures necessary keys are present.
Fix readme info for inclusion of plugin in webpage
1.1.6: Updates to 'data' + 'playbackRate' methods

Also updates to documentation and updated/added unit tests.