Ability to override options with data-toggle-* attributes

Added ability to override options on the element with data attributes:
data-toggle-width="150" 
data-toggle-height="35" 
data-toggle-on="true"

Example: http://jsfiddle.net/yR67u/2/

Couldn't do all w/o significantly changing the code. I think that the most painful is on/off status anyways. 

Fixes #19