[Color] Add Color.fromCSSColor()

Support #rgb, #rrggbb, rgb() and rgba() formats
Update the changelog
[Color] fix CS
[Color] Add support for named colors & hsl[a]()
[Color] Tweaks
[Color] fix regexps
Fix jshint warnings, doc tweak.
Added NamedColors enumeration.
Remove unused dependency.
Fix documentation type for NamedColors.
Rename use of `toCSSColor` to `toCssColorString`. Update CHANGES.md.
Temporary hack (partial rollback) to get code & tests working again until @mramato has a chance to put in the real fix.
Move changes target from b12 to b13.
Add clear method to TileLoadQueue.

Also add tests for TileLoadQueue.
Rename TileLoadQueue.js to TileLoadQueueSpec.js.
Use context.createSampler to create samplers.

Previously, ImageryLayer was building the object literal manually.
Add doc for TileLoadQueue.clear.
Work around Firefox beta/canary worker transferable object bug.

This addresses issue #408.
Additional cleanup, more to come.

1. Delete NamedColors.js and roll it into Color.js
2. Static colors are now actual color instances.
3. fromCssColorString now only takes one parameter and returns undefined for invalid colors.
4. Break out regular expressions and helper functions to be locally scoped.
Final round of changes for CSS color support.  Improved tests and clean up code.