Fixes memory leak in netty-socketio.

* Do not include Mobile in WAR
* Deploy frontends and customization to their own contexts in dev env
* Update Connector and Jetty dependencies

This includes usage of newest connector-client. The last maven based
version 0.41.0 had been replaced by newer 0.7x version wich includes some
new features.

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.

Spring 3.2.2 is less restrictive in view resolving than newer 3.2.3 so
use this until forwarding in ARSnova is fixed to pass 3.2.3.

Jenkins tries to use old version 2.1.1 but this artifact is not
available anymore.