added hideOnStill functionality

[browndp08]

Users now have the ability to hide the scroll button when scrolling ends.

[markgoodyear]

Thanks for the PR, quite like this feature. Would you be able to follow the code style to keep the code base the same throughout? For example, indentation should follow the current 4 space (not tab) indentation. Also checkout the contribution doc for info on how build out the distribution files — I can do this though!

[browndp08]

Absolutely. I'll note that for the future.

[aagouda]

This PR must be add, very important.

[jacklj]

Yes, would be great to get this added. Tiny bug (feature?), if no scrolling has taken place, and the page is already scrolled down (e.g. if you scroll down, then go to another page then press the browser's back button so that the page is returned to at it's previous scrolled-to location), then the scroll button doesn't disappear till you scroll for the first time.

[browndp08]

@markgoodyear I updated the code spacing and used gulp to build the dist folder. Also merged your latest version in. Is there anything else I need to do for you to merge this?