Added Lucene 3.5 dependency for full-text search
Added an Index to the Model, to be updated on model switch or change
Added additional indexed fields using "indexed" instead of "_indexed", to work around naming limitations
Greater efficiency - no longer attempts to index non-indexable objects
Cleared everything in clear()
Re-styled constants
Added comments to all public methods, fields, constants
Merge pull request #109 from manuel-freire/text-search

Added Lucene 3.5 dependency for full-text search