Limit outstanding async requests on a TCP socket.
Merge branch 'master' of github.com:aphyr/riemann-java-client

Conflicts:
	src/main/java/com/aphyr/riemann/client/TcpHandler.java
	src/main/java/com/aphyr/riemann/client/TcpTransport.java
TcpHandler: minor adjustment to queue size check

Not even correct, but it's bugging me.