Add explicit init/close methods to OpendaylightToaster

Add explicit init/close methods to OpendaylightToaster

The blueprint XML specifies the "register" and "unregister" methods
for init/destroy however this bypasses the "close" method. Add
explicit init/close methods and call register/unregister.

I also moved the initialization code that was in setDataBroker to the
new init method. The former is a setter and should have code logic side
effects.

Change-Id: Idf46f76913c4400aaef61ff78ad8f57e3db4c4b9
Signed-off-by: Tom Pantelis <tompantelis@gmail.com>