Added arrow key navigation option

Also updated name of scrollTo function to scrollToSection to avoid issue w/ js's built in scrollTo function
Merge pull request #23 from jimmynotjim/feature/arrow-key-navigation
Merge branch 'v2.0' of https://github.com/jimmynotjim/scrollNav into feature/active-class-update

# Via James Wilson (1) and Jimmy Wilson (1)
* 'v2.0' of https://github.com/jimmynotjim/scrollNav:
  Added arrow key navigation option

Conflicts:
	dist/jquery.scrollNav.js
	dist/jquery.scrollNav.min.js