Bug 1026384 - [MMS]Display switching of SMS/MMS composition screen r=Steve

https://bugzilla.mozilla.org/show_bug.cgi?id=1026384
this doesnt work; for example, when we have images, this will switch back to 'sms' ...

I think we need something more complicated than this, and possibly redo how the type is choosen. I'll try to think of it over the week-end and come up with a solution monday.