Multiple nova consoleauth support

* Added consul service for memcache.
 * Memcache should be a central service in order to use it to store tokens and to
  use multiple consoleauths. So adding a consul service for that.
 * added better test for memcached.
 * Added spec tests
* Added memcached based caching for nova controllers 
 * This is required to support multiple nova consoleauth nodes.
* Fixed issue on configuring private_address/public_address on cp nodes
should we be using every discoverable memcache server? Aren't there some other ones running with contrail, etc. Are we going to also use those to cache sessions?