Make XMPP use the Bioclipse usermanager

It also:
* Removes the XMPP topmenu and preferences page
* Update the cheat sheets according to points above
* Adds help-pages to the help context
* Adds javaDoc and copyright to XwsLoginOutListener.java
Merge pull request #8 from KlasJoenssson/Bug3290

Make XMPP use the Bioclipse usermanager