Don't use memcached_server_add_udp with libmemcached 1.x.

memcached_server_add_udp was deprecated in favor of using the
MEMCACHED_BEHAVIOR_USE_UDP behavior at the whole-pool level and unifying
the server_add functions.
Add myself to docs/coders.rst.
Merge pull request #139 from spladug/udp-connections

Don't use memcached_server_add_udp with libmemcached 1.x.