BUG-1254: fix concurrent add/remove session test

 - replaced executor service with logging impl
 - mock tidy up
 - ipaddress mockery added
 - feature replaced for real object
 - introduced action waiting mechanism based on future results
 - added cleanUp of sessionManager singletons (SalRegistrationManagerTest)
 - extended close functionality of SalRegistrationManagerOFImpl
 - rebased
 - fixed imports

(cherry picked from commit 760fa0e882574dbdb6ab1a677cb526515530403e)
Change-Id: I2e3c26eb37b8f80f85a79b8fed63933eb62ccb96
Signed-off-by: Michal Rehak <mirehak@cisco.com>