Move ProfileStorage() from aa.py to the new profile_storage.py and make
it a class. The variable name in __init__() changes (profile -> self.data),
but the content stays the same.
The ProfileStorage class acts like a dict(), but has some additional
checks for unknown keys in place.
Also add some tests to make sure unknown keys really raise an exception.
Acked-by: Seth Arnold <seth.arnold@canonical.com>
