Merge pull request #178 from miracle2k/router-etcd-init

router: Fix sync with pruned etcd instances.
discoverd,router: Fix etcd fullsync

The newKeys map is used to determine what keys were
deleted since the last sync.

Closes #187

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
Merge remote-tracking branch 'origin/master' into router-miracle2k