support for hierarchical module naming schemes

@geimer: this should fix the problem that's blocking you right now

I might need to figure out one more thing w.r.t. the devel module name before this really works for you, I'm looking into that...
because that's getting too big already...

```
$ wc -l easybuild/framework/easyconfig/easyconfig.py
    1020 easybuild/framework/easyconfig/easyconfig.py
$ wc -l easybuild/framework/easyconfig/tools.py
     470 easybuild/framework/easyconfig/tools.py
```