add CdiEventListener to processApplication by default

changes:
- add transitive dependency to engine-cdi (must be deployed together with the ejb-client.jar so no use in scoping it "provided"
- include the CdiEventListener setup from the web site example

Effect: using the default ejb processApplication enables cdi eventing by default without the need to write and deploy a custom PA.
Figuring out the correct usage took some time and I dont want to write a custom processApplication for every JEE/BPM project.

discussion:

- EJB is not CDI so one could argue that this is breaking, since I could run on a container not supporting CDI. But is pure JEE5 a supported platform for 7.2.0?
- Performance: a view events get fired even if no one is listening.  Idea: enable/disable via configuration. How about checking if the ProcessApplicationEventListenerPlugin is enabled? How can I access the processEngineConfiguration from within the ProcessApplication to check?