Analyser dependencies

I did run the analyzer on my app, output was:
- Analyze with pdepend … Done
- Analyze with calc … Done
- Analyze with phpmd … Done
- Analyze with diff … Done
- Analyze with uml … Done
- Analyze with phpcpd … Done

well one thinks all is ok, but when I tried to see the class diagram:
"Analyzer not available

The analyzer UML is not available. It had been disabled during source analyzing."

checked my results directory and I saw the uml.dot ... well .. ".dot" for me means "I need graphviz" ...

installed, rerun the analyzer (exactly same output as the previous one), and the class diagram is now available ...

Should be good to:

1. get an exception running the uml analyzer if graphviz is not present
2. add "graphviz" as dependency