WIP: Optimize database performance

@abinoda We are currently in the process of adding the appropriate callbacks to update the karma_points_sum column.

We have completed the first two tasks, but our speed is still a bit above 300 ms. Are we missing anything?

Added Indexes and Sum Column: 
![screen shot 2013-09-02 at 3 04 02 pm](https://f.cloud.github.com/assets/3926767/1069128/d9f05a78-140a-11e3-837c-15f5fde64a25.png)

Updated Methods:
![screen shot 2013-09-02 at 3 04 34 pm](https://f.cloud.github.com/assets/3926767/1069131/fc45c28e-140a-11e3-957d-c76a120a3efe.png)

Seeded DB with Rake Task: 
![screen shot 2013-09-02 at 2 47 22 pm](https://f.cloud.github.com/assets/3926767/1069133/085ba002-140b-11e3-9701-72df0047b33c.png)