Free/unreserve VLANs after use

[sajith]

Grabbing an issue for these TODO items:

pce/src/sdx/pce/topology/temanager.py

Lines 651 to 663 in 1e19555

	def _unreserve_vlan_breakdown(self, break_down):
	# TODO: implement this
	# with self._topology_lock:
	# pass
	assert False, "Not implemented"
	def _unreserve_vlan(self, domain: str, port: dict, tag=None):
	"""
	Mark a VLAN tag as not in use.
	"""
	# with self._topology_lock:
	# pass
	assert False, "Not implemented"

Currently SDX Controller has not implemented DELETE /connection fully though, so that too will need to happen for this to be useful.