Turned on the TCP_NODELAY socket option (disables Nagle's algorithm)

Tests show an 8-20 fold improvement in throughput. Messages under 1500 total
bytes benefit the most. Even with messages of 10K in size there's still a 30%
improvement in throughput; that's a lot. Tested with JRuby 1.7.3 and Ruby EE
1.9.3 on RHEL 6.1 against ActiveMQ 5.8.0 (also running on RHEL 6.1).

Default is true, but can TCP_NODELAY can be turned off by putting :tcp_nodelay
=> false in the parameters hash.

(ppaul/6540400, #8)