Use EntityBareJid just as its done within PepManager. There is no need
for AsyncButOrdered in the PEP user managers, as PepManager already
takes care of that. Also the message carrying the PEP event should
always be the last parameter of the callbacks, as it is the least
important piece of information.
This mini assignment kicked-off with replacing `pubsub` with `pep`,
but later transformed into something more.
The alterations and additions in this commit:
a) GeoLocation.
1) Add Documentation.
2) Add `EMPTY_GEO_LOCATION` to be used while
`stopPublishingGeoLocation()` is called.
b) Add GeoLocation IntegrationTest.
c) Add GeoLocation Listener.
d) GeoLocationManager.
1) Add Documentation.
2) Replace `pubsub` with `pep`.
3) Add methods to add-and-remove GeoLocationListeners.
4) Enable GeoLocation by default.
e) Add `package.info` for GeoLocation Integration Test.
Paul Schaub
