Have annotations as their one Java project

This simplifies and cleans the build files for the realm and
realm-annotations-processor projects. It also makes IDEs more
willing to cooperate when working on the realm-annotations-processor
project since before they were complaining about not being able to
open a project with out-of-project source-sets.
Add missing dependency
Make the annotations available to the annotations processor during tests
Remove auto generated comments
Merge pull request #536 from realm/ez-annotations-jar

Have annotations as their own Java project