Redesign of registration process.

I've redesigned the "registration" flow to hopefully be more accommodating.  This should also set the stage for allowing the user to manually enter a verification code in the future.  Please look critically at this change, since it's something we really don't want to fuck up.

1) Added a country selector and as-you-type number formatting.

2) Split out the registration progress into a separate "modal"
   activity that explains what is happening and gives deterministic
   progress.

3) Put the logic into a service, with the Activity serving as a view
   for the service, which should allow users to change focus without
   any adverse effects.

4) Redesigned the look to be hopefully less ugly.

5) Allow processing in background, with a notification on error/success
   if the registration activity is not in focus.