[GNOME] SIP TCP protocol support

Issue generated from Tuleap's migration script. Originally submitted by: Óvári (ovari)

SIP providers recommended different SIP Transport settings. For example:
* Transport: Leave UDP for desktop, select TCP if you are using on your mobile or via mobile connection

1. Would you please enable GNU Ring to allow UDP and TCP transport selection for SIP accounts?

Linphone (http://linphone.org/) provides the following transport options:
* UDP (User Datagram Protocol)
* TCP (Transmission Control Protocol)
* TLS (Transport Layer Security)
* DTLS (Datagram Transport Layer Security)
2. Can code from Linphone be used in GNU Ring?

3. Does this apply to other platforms, i.e. Android?
4. If so, does the platform for this ticket need to be changed to “Any”?

Thank you