Check if `value` has changed

Fixes a issue that the `change` event was triggered on `init` and on
`resize`. Implements a check if `value` has changed before it fires the
`change` event.
Updates the example value feedback functionality

To trigger this functionality on load, because there isn’t a change
event on load anymore.
merge develop into trigger-change-only-on-value-change
Merge branch 'develop' into trigger-change-only-on-value-change

* develop:
  Swaps the order `onInit` is executed before `update`

Conflicts:
	dist/rangeslider.min.js
Merge pull request #67 from andreruffert/trigger-change-only-on-value-change

Trigger change event only on value changes