Avoid infinite recursion when creating ConfigData objects

Overriding `__setattr__` and `__getattr__` made the assigment in `__init__` enter into infinite recursion. I use `object`'s `__setattr__` for bypassing `ConfigData`'s.

I tried to push to the upstream repo but for some reason I didn't have permission even though I'm member of the @taigaio organization, @bameda can you give me commit rights on the repo?  Pleeeease :cake: