added priority ratings for tasks

I'm new to the whole github thing, but I added a priority rating system to your plugin
![screen shot 2013-07-21 at 20 50](https://f.cloud.github.com/assets/2246606/832640/ca0c4fe0-f268-11e2-962f-6e93eac44006.PNG)

I also plan to further enhance this plugin to include a user page where users can view all of the tasks related to them among some other as of yet undetermined modifications.