Fix #663

Return all healthy minions instead of only returning the first several
healthy minions. Without the PR, if the first minion failed with health
check, the machine list is empty, thus GET /api/v1beta1/pods failed
with code 500
Make file error logging edge triggered to reduce log spam.
Cleanly delete service without endpoints key

If a service is deleted before the etcd key corresponding to its
endpoints has been created, a 500 error is returned (etcd key
not found).  Instead, key not found should be ignored silently.

There is a potential race condition with the controller creating
endpoints after the service has been deleted which a cleanup task
should handle in the future.

Closes #684
Merge pull request #681 from brendandburns/noisy

Make file error logging edge triggered to reduce log spam.
Merge pull request #679 from dchen1107/minionlogs

Fix #663
Merge pull request #685 from smarterclayton/error_on_empty_service

Cleanly delete service without endpoints key