Vaadin v73 version fixed

Vaadin version v73 fixed
Commented out dependencies
Downgraded to jbpm&drools 6.1.0
Corrected versions in p2 pom
Further dependency fixes; build seems stable
Vaadin 7.3 p2 should work now
Added dependency to p2 pom
Added org.json to Vaadin 7.3 feature
Added Guava annotations to Vaadin 73 feature
Fixed feature dependency
Merge pull request #2 from klemensedler/master

applying Further fixes in dependencies