Issue #624 - Truncate the titlebar button's text when it overflows

Fixed the issue by setting the max-width of the title-bar button to 253px. 
Now the button with long text will take at most half of the title-bar.
Tested on both ripple and the device. 
![Screen Shot 2013-02-05 at 8 28 48 PM](https://f.cloud.github.com/assets/1450914/130343/c748c9c6-7015-11e2-8ca8-463aa2c0b7ac.png)