The start method is run everytime a new object is created, which
includes when it is first loaded into the MOZ or upgraded, as well
as at other times in some cases.
The start method is normally either passed the boolean
isForUpgrade feature if the start is being run during an
upgrade (which can require special processing) or nothing at all.
stop
The stop method works like the start method in all respects except
that it is run before the object is shut down or upgraded.