Integrate dbfit and fitnesse wikidocs

This is related to #13 

- [x] Make DbFit wiki docs auto-expandable by FitNesse (alongside the core FitNesse docs)
- [x] Remove `-o` option from `startFitnesse` shell scripts. This way bundled FitNesse docs will be expanded and also DbFit docs will be expanded too when using `-d`. It's still possible to override this by passing `-o` argument to shell scripts.
- [x] Modify DbFit wiki docs front page so that it includes reference to FitNesse core docs.