Added UDP support

Created Graphite::Socket to add UDP support. This includes defining
default port configurations, in addition to updating tests to
understand UDP mocks and UDP operations.

Graphite::Socket is based in part on work from the MIT licensed gem
"logstash-logger", by David Butler. The new features should be
drop-in and backwards compatable.
Merge pull request #6 from mckern/udp_support

Add UDP support