moving to 2.11.0

- bumped version
- fixed some deprecations
- moved ZooKeeper experiment to its own project (waiting for twitter to publish 2.11 libs)
- setup build for publishing both in 2.10.3 and 2.11.0 (use `+compile` or `+publish` in sbt for running over all declared versions). See [sbt doc](http://www.scala-sbt.org/release/docs/Detailed-Topics/Cross-Build) and [this sample](https://github.com/scala/scala-module-dependency-sample).
- removed coverage lib until it's 2.11 compatible