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
Adds the help-pages, their images and the tox.xml to the build
Merge pull request #9 from KlasJoenssson/Bug3290

Adds the help-pages, their images and the tox.xml to the build
Make use of the possibility to test the settings before creating a
XMPP-account
Merge pull request #10 from KlasJoenssson/Bug3271

Make use of the possibility to test the settings
Updates the help page "Adding a XMPP-account to Bioclipse" with respect
to the new test log-in button.
Fixes some spelling misses
Merge pull request #11 from KlasJoenssson/Bug3495

Updates the help pages
Removes udpate2.bioclips.net from p2 available sites

see bug 3486
Add releng component for building with buckminster

This enables mirroring of the p2.site using p2 actions from buckminster
This file also contians extra dependencies needed to build the bundles in this repo
Removes slf4j.api from feature
Updates bundle versions to 2.6.1
Feature version set to 2.6.1
Removed version from org.slf4j

To allow for updates to 1.7.5
Release 2.6.1

Merge branch '2.6.1'