[BUGFIX beta] HashLocation no longer looks the hash up with location.hash because of a Firefox decode bug. Fixes #4262

HashLocation no longer looks the hash up with location.hash because of a Firefox decode bug. Fixes #4262

https://github.com/emberjs/ember.js/pull/4008 fixed this [here](https://github.com/emberjs/ember.js/blob/master/packages/ember-routing/lib/location/hash_location.js#L31), but since the `query-params-new` feature may or may not land in a stable release for some time, I think this should be fixed separately without being behind that feature flag.

Technically, this PR fixes this issue with the yet-to-be-released `AutoLocation` as well. I can break that out into a separate PR if you'd like, no problem. The common helper between the two was made at `Ember.Location.getHash()` since it seemed logical IMO.

If anyone can think of a way to test this...I'm all ears. Coverage on all the `Location` classes is lacking, as is already known. (on my bucket list as well)