Add to the endpoint list, valid endpoints setup by users.

[Natim]

Sometime the auto-discovery doesn't work because of network routers or firewall so we want to keep endpoint entered by users.

Maybe we should write that to a file so that after a circushttpd restart we can reload that list.

We could also have a page with a green light and red light of each endpoint and something to delete/edit/rename the endpoint and monitor the circusd all at once.

[Natim]

We could implement the unicast discovery for that: http://www.elasticsearch.org/guide/reference/modules/discovery/zen/

Or use the circusd discovery so that we can ask for cluster discovery on the first connected endpoint using a request on tcp://ip:5555/ so that if the circushttpd is not on the same network it can still use the circusd cluster discovery.