feat($location): add support for state and title in pushState

This is a continuation of #3325, re-created per my e-mail thread with @IgorMinar.

Adds $location pushState & replaceState methods acting as proxies to history
pushState & replaceState methods. This allows using pushState to change state
and title as well as URL. Note that these methods are not compatible with
browsers not supporting the HTML5 History API, e.g. IE 9.
I was following the `lastBrowserUrl` pattern, I assume it was needed purely to compare to the previous URL?