Fixes #195

RxClient.shutdown() was shutting down the eventloop.

This caused the following scenario impossible to work:

1) Create some clients
2) Shutdown all of them
3) Create another client & try to use it.

In the above scenario, at stage 3, the eventloop is shutdown and hence can not be used by the newly created client.

Removing the eventloop shutdown. Since, the eventloop is always a daemon, shutting it down isn't really necessary.
We will think about graceful JVM shutdown scenarios and hence a need to provide a global shutdown on RxNetty later.
Merge branch 'master' of https://github.com/Netflix/RxNetty
Updates CHANGES.md for 0.3.11
Merge pull request #197 from NiteshKant/master

Fixes #195
[Gradle Release Plugin] - new version commit:  '0.3.12'.
Fix copy/paste error in documentation.
Merge pull request #200 from gorzell/master

Fix copy/paste error in documentation.
WebSockets - first version.

The implementation is mostly complete, and ready for the review.
Metrics are still to be implemented.
Remove WebSocketFrame wrapper classes.
WebSocket metrics.