(#20) Update submodules.
(#20) Track STOMP connection state.

Upon disconnect, dump any buffered metrics. On receipt of metrics and we're
disconnected, drop them on the floor, (but still increment the Rx counters).
(#20) Forgot enqueue.h
(#20) Bump release number for RPM.
(#20) Add basic signal handling

Ignore SIGPIPE and set up basic handler for SIG{HUP,INT,TERM}.