Make Felix's etcd watching thread more cooperative.
Make Felix's etcd watching thread more cooperative.

neiljerram/felix,neiljerram/felix,TrimBiggs/calico,neiljerram/felix,Metaswitch/calico,Metaswitch/calico,alexhersh/calico,neiljerram/felix,TrimBiggs/calico,matthewdupre/felix,alexhersh/calico,matthewdupre/felix