Apply more jshint options.
Build unminified version of vtt.js as well.

This is useful for development builds.
VTTRegion scroll setting should be "" not "none".
Only swallow errors that the parser uses to manage its state.
Cues should have a default line alignment of start.
Implement a full shim for the VTTCue WebIDL.
Implement a full shim for the VTTRegion WebIDL.
Extend VTTCue/Region with methods needed for testing and NodeVTT.

- Be able to convert VTTCues/Regions to and from JSON. Remove properties
that aren't needed in JSON format of VTTCues such as _reset,
getCueAsHTML(), and displayState.
- Be able to construct VTTCues/Regions from option objects.
Fix accidental change of fromJSON() to create().
Version 0.5.0
Update processing model to reflect changes in the spec.

These include changes for the new line alignment and position
alignment settings.
Cue2json should write processing model tests to different JSON filename.
Add processing model tests.
Update README with processing model changes.