Reload individual rows instead of an entire section for subsection

Closes #81 

Instead of reloading the entire section when the segmented control changes, only reload the title row and delete/insert the rest of the rows.  The "after" animation below was captured before the additional action of reloading the title row was completed.

## Before
![before](https://cloud.githubusercontent.com/assets/373903/5527634/d4496fc4-89c5-11e4-824e-de53a5be4c3d.gif)

## After
![after](https://cloud.githubusercontent.com/assets/373903/5527635/d44f07c2-89c5-11e4-923c-26159ab8f4b7.gif)