add/write small scroll lib to make section linking scroll smoothly

[tomhuhges]

if you feel like writing your own smooth scrolling function then feel free.

otherwise add a library that isn't too big. we currently don't have gulp set up (see #7), so it will have to be included in a script tag until that issue is completed.

[danmarcus111]

I think Rahul is planning to write this over the next week