TAP5-2051: Remove unecessary references to PlasticClass objects

Replace anonymous inline inner classes with static inner classes to eliminate hidden references to PlasticClass and other transformation-time objects
Add a ControlGroup mixin for Field components

Adds the outer divs and label for a field to work well with Twitter Bootstrap
Minor documentation updates
Minor typo
Add IOOperation and OperationTracker.perform()
Streamline the code inside OperationTrackerImpl
Improve documentation
Rewrite URLs inside CSS files to be absolute (via AssetSource)