Add Query Bean support with io.Ebean dependency

[felipebonezi]

Ref #64
Fixes #61

[felipebonezi]

@octonato @benmccann @marcospereira
I'm stuck, can you help me?

1. I'm using io.ebean dependency to use Annotation Processor for create Query Bean classes. Do you think is a good approach?
2. I don't feel that my code to generate Query Bean classes are good. How can I execute shell script when an settingKey are true? See more here
3. How can I test? I've created at sbt-play-ebean/sbt-tests folder a new project, but I don't know how to run it.

[octonato]

@felipebonezi, I'm not much involved with this library and I don't know the internals either. I prefer to defer to the community members maintaining it.

Concerning the call to javac from inside sbt, I don't think that's a good idea. sbt compiles java code already.

You may be interested on this sbt documentation page.