[WIP] Fix getattr, setattr and getitem.
[WIP] Fix getattr, setattr and getitem.

__getattr__ is only called if the attribute in question is not in the
dict. Therefore, use __getattribute__. But, it has to pass control on
to the parent if the accessed attribute is not controlled by LDAPConn.

__setattr__ also has to pass control on in order to not break things.

__contains__, __getitem__ and __setitem__ allow for dictionary access,
__but *only* to attributes controlled by LDAPConn.

rroemhild/flask-ldapconn