__conform__ should not require a store

[Laurens Van Houtven]

 Empowered.__conform__ gives up if there is no store. That makes sense
for persisted powerups (obviously), but it means that the following
doesn't work:

    >>> rodimus = Transformer(name=u"Rodimus Prime", damage=50)
    >>> hotRod = HotRod(color=u"Red and yellow")
    >>> rodimus.inMemoryPowerUp(hotRod, ICar)
    >>> assert ICar(rodimus) is hotRod
    Traceback (most recent call last):
    ...
    TypeError: ('Could not adapt', ...)

You can see this in action here:
https://travis-ci.org/lvh/axiombook/builds/4628027

The reason it doesn't work is that __conform__ craps out.

I think this is a bug, because the docstring for __conform__ appears
to suggest that it should just use the first powerup from powerupsFor;
but that uses _inMemoryPowerups before looking at stored powerups,
exactly as the inMemoryPowerup docstring suggests as well.

[Laurens Van Houtven (lvh)]

Does anything still needs to happen for this to be able to be merged? ISTR that this was hashed out on the mailing list and that it was good to go.

[Tristan Seligmann (mithrandi)]

In fact this was merged, I just forgot to close the bug.