lib/logstash/outputs/udp: Another fix; stop leaking FDs in UDP output.

Presumably the TCP output has the same problem as this, but we don't
use that one, and we *do* use UDP.  For some reason, the Client isn't
getting reused between messages and thus we're creating new UDPSockets
which leak all over the place with FDs, eventually failing to send
any new events.

Fix this with a terribly inefficient open/close of the socket for
each UDP transmission, but I guess that will do until I rewrite this
shit software.
lib/logstash/version: Bump PD-internal version again.
lib/logstash/outputs/udp: 'ensure' socket closing happens.

On Simon's suggestion; we make *sure* to execute the close, no matter
what exceptions propagate up to try to sabotage us.
Merge pull request #3 from PagerDuty/udp-fixes

UDP fixes (fix for too many open files); CR'd by James/Simon.