chore($sniffer): Remove $sniffer.hashchange

The hashchange event is not supported only in ancient browsers like Android<2.2
and IE<8. Angular never really supported IE7 and in 1.3 where support for IE8
is dropped it makes even less sense to check for hashchange support.
@caitp not URL pooling, just `$browser.addPollFn`.

Obviously it could be moved to `ngCookies` but see what @IgorMinar said above.