Add Interpreter Support for Exception/Finally Guards

```
the interpreter cannot handle EdgeGuard.EXCEPTION and FINALLY right now.

see 
'/org.storydriven.storydiagrams.interpreter.tests/resources/activities/Exception
FinallyGuard.sdm'
```

Original issue reported on code.google.com by `aljoschability` on 23 Jul 2012 at 10:47
