[bug 932333] Delete RegistrationProfile during user activation.

This ended up being way easier than I thought.

The problem was that when we cleaned out the RegistrationProfiles as they expired, we were deleting users that never activated along with users that had activated and contributed but then had been deactivated. This patch takes care of that second case. As soon as a user is activated, we delete their RegistrationProfile. Now the cron job only cleans up RegistrationProfiles for users that never activated which is what we want.

r?