Fix button access checks
Fix button access checks

Some buttons (such as 'button_claim' are _set_ unconditionally,
although they sometimes are set to a False value. Therefor, simply
checking if they are in the buttons dictionary is not sufficient, we
must explicitly check if they are True.

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son