Annotation support

adds support for custom annotations on generated classes, constructors, fields and getter/setter methods. issue #66.

this pull request is a re-implementation from [Path's fork of GreenDao](https://github.com/path/greenDAO) . specifically [commit d3deaf](https://github.com/path/greenDAO/commit/d3deaf3051da9ac106bfb6cd1324caa19ddc04a6)

I could not make the eclipse formatting work in Intellij 12 so sorry about the formatting diff.