southbound should only monitor Open_vSwitch tables

The patch also adds more clear logging to indicate connection events and indicate which direction the events happened.

Patch Set 4: Review comments. Remove the filter since it doesn't make sense because the caller is asking explictly for the table to monitor.
Patch Set 2, 3: fix unit tests and update commit message

Change-Id: I4ea511906911bf9296e78f57f1b63dc2608c9501
Signed-off-by: Sam Hague <shague@redhat.com>