Mms: Add the ability to select recipients from a checkbox list

When creating a new message you have to write some letters from the
contacts you want to add and select them by clicking on it.

This can be annoying if you want to send your message to several contacts.
With this change you can manually select numbers from contacts and groups
from a checkbox list.

Change-Id: I15ef967f98972640b69e21d41e2f92e56662b6ec
Cleanup: Remove variables that were never read.

Change-Id: Ie5c0a52ce75dbed129ed499fa6babb49b325fd8f