Error types to determine when a server is down
Init with consisten hashing
Glock Client to handle multiple glockServers

Glock Client will handle multipel glock servers, if one server drops
due to a connection error, the client will drop the server from its
consistent hashing list. And then recursively attempt to lock again.

All consistent hashing calls are already protected by a lock inside the
library so we don't need to do any mutex locking while using them.
Check endpoint status first before adding into the hash table
Merge pull request #9 from iron-io/feature-consistent-hashing

Glock client to handle multiple glock servers using consistent hashing