Changed voting so that users score cant be minus.

This does not affect post/comment scores which can be minus numbers.
This stops people who don't like a certain user making it impossible from
getting out of negative numbers. It may still stop them from getting more
than 0 though, but it doesn't look as bad at first glance.
Added credits section to README so that I can give James credit for illustrating our Otter logo
Added stub view and template for alerts.

These stubs have been added ready for work on the alerts (notification) system.