Expander text look well centered in iOS. Also, now using a real minus sign

## Before

![photo 2](https://f.cloud.github.com/assets/85783/661803/f520346a-d73f-11e2-833b-bf0d9fcde2ac.png)


## After

![photo 3](https://f.cloud.github.com/assets/85783/661804/f76e02ec-d73f-11e2-8cc0-12edf9601e83.png)

![lion](http://media.heavy.com/media/2012/08/tumblr_m3gqteybrJ1qc0cxpo1_250.gif)