This is a workaround when a session keyword is entered as a single key

Lots of redundand code deleted thanks to this change

Feedback is stored in memory on the server, and not inside
CouchDB any more.

Removed netty dependency. It is only needed by netty-socketio and should
not be required in our POM explicitly.
Updated jackson-databind dependency to version 2.2.2.

These changes hopefully fix the threading problems with redeployment on
Tomcat 7.

Connector bean has to be disabled because connector could not get any
connection to database server. Connection to database server is
forbidden.

It is required to setup those values after login. Current session
information will be set up after joining a session.

Renamed TEACHER to SPEAKER to adapt roles to ARSnova client, and
also added some convenience methods for role handling.

These URIs should not be requested if user does not successfully join a
ARSnova session.

One more thing that allready should have been in documentation but
drives developers and admins into madness.

This should prevent concurrent ConcurrentModificationException after
application lock on undeploy.