Improvements over limits change situations.

Hello Guys,

I needed to use a slider implemented solely on angularjs and see yours and satisfied my needs.
Although when using it I found a couple of issues which I describe below.

First, the components renders fine the first time. When you change the min/max values the component adapts properly, but not when you change the min/max limits (ceil, floor). In that case the component remains inconsistent.

Second, I needed to use the component inside tabs, each tab (bootstrap) contained a slider. I ran into an issue where the second tab (invisible) render the component wrong. So I added a small mechanism, a flag basically (might not be the most elegant) to force the component re-render when switching tabs.

I think I made a mistake re-indenting the code via IDE, because now seems like the whole file has been changed.

Summary of changes:
- Also adding a force re-render mechanism useful when using tabs.
- Adapting component to render properly on min/max limits changed.