UTs: Disable auto deletion of ports/subnets/nets

Change the behavior of the unit test context managers
for ports, networks, and subnets to skip the deletion
of the objects they create.

Adds explicit delete calls to the tests that require
deletion of the objects.

This is the first patch in a series to eliminate the
automatic deletion of objects created during tests to
improve test performance and make testing more explicit.

Implements: blueprint remove-unit-test-autodeletion
Change-Id: Ifc4490b121310ad64e18936e6fd94a2c9a1e36f2
ofagent: Clean up logging

- Use _LI, _LW, _LE
- Remove localization from debug logs
- Replace LOG.debug calls with @log.log decorator where appropriate

Change-Id: I9c80c556003db7b0b8e99da0340a26beb1e00e16
ofagent: Remove broken XenAPI support

ofagent has code for agent-on-DomU support inherited from OVS agent.
However, it's incomplete and broken.  Because ofagent uses a direct
OpenFlow channel instead of ovs-ofctl command to program a switch,
the method to use the special rootwrap can not work.

Closes-Bug: #1368006
Change-Id: I0bb25a296d1f1e65c233ece6deaef6c095d78707
Merge "ofagent: Clean up logging"
Merge "ofagent: Remove broken XenAPI support"
Merge "UTs: Disable auto deletion of ports/subnets/nets"