Bump Ember to 1.5.1 to get Auto/HistoryLocation fixes

Noticed you're using `location: "auto"`, which is *awesome*, but unfortunately 1.5.0 shipped missing an important commit and while we were at it we fixed a few other things found. In (semver) theory, should be a fully compatible upgrade. Without it--IE9 and lower routing is bonkers in certain situations.

https://github.com/emberjs/ember.js/blob/v1.5.1/CHANGELOG.md#ember-151-april-22-2014

![Oops I did it again](http://www.reactiongifs.com/wp-content/uploads/2014/01/rudd.gif)