Consolidate duplicate logging messages.

Change-Id: If66df6f9b42cbfb00f8ed2d81e573a550c3e6db3
Make cleanupServer optionally nonblocking.

cleanupServer is used from both the CLI and the daemon, but in the
daemon we don't want to block - a single slow to delete server should
not block deleting all other servers. Instead we want to pass over all
the servers we have pending deletion, submitting them for deletion,
and after that loop back and check that they were in fact deleted. Or
not.

This change also fixes a minor bug where calling cleanupServer on a
server that was concurrently deleted from the provider (e.g. by the
CLI) would result in a traceback and deferral to the next loop of
periodic cleanup before the node record was deleted.

Change-Id: If40930238d82c1103b83fe7f46ef6f6e86efd624
Split out the logic for deleting a nodedb node.

In order to move to scatter-gather, we need to be able to run just the
tail of deleteNode independently.

Change-Id: If03753e98b423552c8fd6be4d2f5b6b543f3a1af
Merge "Consolidate duplicate logging messages."
Merge "Make cleanupServer optionally nonblocking."
Merge "Split out the logic for deleting a nodedb node."