Netty updates


* Bumped Netty version
* Applied socket settings to Netty
* Made initial connection async but will block on first read / write
* Made AsynchronousSocketChannelStream inline with other streams 
  it now throws a MongoSocketOpenException if connection fails

Refs JAVA-1155
I don't think you need to ensureOpen on a read, since according to MongoDB protocol, a read is never the first operation on a socket.  A write is always first.