Feature/add gomemcache

Add optional golang based gomemcache library. 
This library does not require libmemcached, and provides it's own pooling, but does not offer the level of control that gomc does. This library has NOT yet been fully load tested.

@bbangert || @kitcambridge r?
II think this is an old comment, removing it because it's confusing.

Exists() merely checks to see if fetchChannelIDs returns nil for error, ChanelIDs is an array of arrays, so returning nil is valid and shouldn't require unnecessary allocs. That said, I can remove fetchAppIDArray from Exists (since we can just poll the UAID), and drop fetchChannelIDs since it's only used by fetchAppIDArray.