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...
That's OK imho, since then these errors will still occur even when a fully parsed easyconfig file (i.e. an `EasyConfig` instance) is passed on a second attempt.
This is also checked for by the unit tests (see `test_module_naming_scheme`, where `BrokenModuleNamingScheme` is being tested).

We're basically catching two types of errors that may (or probably) indicate that a fully parsed easyconfig is required, and retry with a fully parsed easyconfig a 2nd time. If some error still occurs the 2nd time, the module naming scheme implementation has a bug, and a proper error message will be spit out.