bug 6579 removed boilerplate code

bug 6579 removed boilerplate code

removed the boilerplate code from commands moved it to super class
pulled the methods extractUpdated and extractRemoved to super class
child class implements getData and areEqual methods

extractUpdated method compares old data and new data and returns the
change set.
Comparison logic is taken care by the sub class.

extractDeleted gets the deleted keys .
for local ucast mac remove command ,If logical switch is deleted ,
it will return the local ucast macs to be deleted aswell.

logical switch removal is fired in seperate transaction to avoid
failure of transaction because of some local references which odl is not
aware of sometimes due to racing conditions.

if mcast mac locator set gets emptied , fire removal of mcast mac
if the json rpc transaction fails, clear the intransit data from device
info

Change-Id: Ia172b5887887f202ba1149ba748862d86f9c9869
Signed-off-by: K.V Suneelu Verma <k.v.suneelu.verma@ericsson.com>