fix(registry): Use cache host and port from confd

The registry was crashing when trying to read cache settings from unset environment variables.
confd is now also population those settings. Fixes #724

I also disabled the LRU cache as this would require to set Redis into LRU mode: http://redis.io/topics/config and this is maybe not what you want for the controller. So the registry is not using redis as a file cache today. As the controller is using redisdb 0, I configured the registry to be 1 to avoid namespace clashes.

I'm currently struggling with setting up my local Vagrant, but I thought I could give this a shoot.