annotating controllers with @Alternative

I've annotated every controller with `@Alternative` and the user of the plugin should enable what controller he needs to use in the beans.xml.

If we don't annotate it with `@Alternative`, the user needs to provide implementations for all the interfaces used by these controllers (`MonitorAwareUser`, `HibernateStatsAwareUser`, ...). Currently, if the plugin user don't implement those interfaces, the application will throw the following exceptions:
https://gist.github.com/csokol/28cdd94ec8190570b5ef