Correct Metrics for SegmentedControl Divider images

The previous assets caused the individual segment to have extra padding on one side. This fixes that behaviour so setting a width to the tabbedBar in Ti displays the element as expected.

Screenshot:
![screen shot 2013-06-20 at 2 01 01 pm](https://f.cloud.github.com/assets/867981/680026/c658f680-d983-11e2-8331-daabf3bb5910.png)