Support device provisioning

[janimo]

When upstream Android and Chrome apps implement multi-device sync, add support for it and make sure we interoperate with those.

[onny]

It's already working with latest Android app version by associating and opening ts://-uris. After that Textsecure-Browser starts syncing messages and contacts!

[janimo]

I tried that pairing procedure a while ago but it was not clear to me it worked. I thought it was not yet finished and tested on the staging server only.

[abarisani]

Any updates on this? It would be nice to have for our INTERLOCK app :)

[evilsocket]

+1 for the INTERLOCK integration

[janimo]

The recent changes by @aebruno implement the 'master' side of the provisioning protocol, the one usually done by the Android client.

[aparcar]

Plans to use the app as a client only? Smartphone as main device