Seems like AngularJS folks are working on it in version 1.3.0.
All you need to do is adding : 'UTC'
after the format string. Something like:
{{someDate | date:'d MMMM yyyy' : 'UTC'}}
As you can see in the docs, you can also play with it here:
Plunker example
BTW, I think there is a bug with the Z parameter, since it still show local timezone even with ‘UTC’.