Cdist fails silently when there's a directory in __type/parameter/default

I just spent one hour on this bug. I couldn't figure out why cdist was ignoring my default parameters.

After investigating on the bug myself, and thanks to the code being very well structured. I found out where was the bug. I wrote a test case, and fixed it.

I assumed that cdist shouldn't be bothered if there's a subdirectory in `__type/parameter/default/`, and it should just keep carrying its own business. Please let me know if this behavior is not the one you want, i'll change my fix.

Thank you.