Remove duplicate source of truth with buffers.

This fixes #73 and is a permanent fix to the bug (#214) that was introduced with #169.

The bug was caused by when `models.reinitialize()` creates a new empty object to `models.model.buffers`, `$scope.buffers` does not get the new object reference which causes a duplicate source of truth with the `$scope` object containing the outdated data. This fix makes the `$scope` attribute a reference to the `models.getBuffers` method. I renamed the `$scope` attribute from `buffers` to `getBuffers` in order to distinguish that it is associated with that method and not the property.