Improve how ActivationResults work

[fohrloop]

in current 0.8.0dev version, the ActivationResult may be initiated without any arguments.

>>> res = ActivationResult()
>>> res.success
False
>>> res.failure
True
>>> res.modename
>>> res.real_success
False
>>> res.active_method
>>> 

Otherwise fine, but the res.failure being True seems odd. Perhaps make res.success, res.failure and res.real_success all be None if the ActivationResult has no ._method_results at all?