Angular resources for anchor smooth scrolling
* Scroll to new hash value with changed location hash otherwise,
* if hash value is not changed, anchorScroll to the given hash.
* This service facilitated with two scrolling methods:
* 1. scrollTo: scroll to hash value without transition.
* 2. smoothScrollTo: scroll to hash value with smooth transition.
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Demo link: http://codepen.io/nimish-mehta/pen/raMjrG?editors=101