Slight refactoring of the lifecycle of data

Slight refactoring of the lifecycle of data

With this patch, we change slightly the manner in which we handle
data change events (including connections)

Previously, when we got a DataChangeEvent we'd try the following

1)  connect(changes) - do all the work for connecting, including
     registeringCallbacks
2)  connectionUpdate - handle connection updates
3)  updateData - use transact to write any data changes to the ovsdb instance
4)  disconnect - disconnect anything if needed

Now we have changed this so that
a)  #1 (connect) - does *not* registerCallbacks
b)  Added a 5) registerCallbacks

The reason this was done is so that the normal pipeline for writing data
can handle flushing the externalId for the OpenVSwitch table down to ovsdb
*before* we registerCallbacks and have it come back to the operational data
store.

Conflicts:
	southbound/southbound-impl/src/main/java/org/opendaylight/ovsdb/southbound/OvsdbConnectionInstance.java

Change-Id: I105dd01bf87b1be170e2c4082a7914fba2002249
Signed-off-by: Ed Warnicke <hagbard@gmail.com>
Signed-off-by: Sam Hague <shague@redhat.com>