Resilient watches

Got some help in #coreos to find out what to do about 401 errors. Turns out the answer is to restart the watch with a fresh Get. That ensures metafora will never miss events.

The diff looks like an absolute mess. Basically all I did was put *another* for loop around the initial Get when we start watching, and have 401s continue that outer loop.


bleh
It shouldn't matter too much, it just needs to be less than `e.nodePathTTL` so that the refresher updates the node's ttl before etcd expires it.   Since we don't use the nodepath for failover detection (we use the claim token), we should be able to set the `nodePathTTL` and the refresh `ttl` to something that is very large.