MT Auth (SMS) and confirm PIN UI

This will need some more polish in subsequent branches but there's enough here to be moving foward with.

I'll hook up more behaviour (changing the operator select) in a follow-up branch.

Here's a demo of the interactions on an emulator: https://www.dropbox.com/s/463nwg4zikj7x90/original-order.mp4

![confirm_your_mobile_number-2 copy](https://f.cloud.github.com/assets/1514/2011963/74b4223e-8782-11e3-83fc-409ba49318dd.png)

![confirm_your_mobile_number 2](https://f.cloud.github.com/assets/1514/1997676/82b21e06-8528-11e3-86f9-a3de7a05f326.png)