New Telephony spec after the editor's meeting

On the editor's meeting in Madrid this version of the specification was drafted, with added support for multiple SIM cards/telephony services, and multi-party calls (as well as out-of-the box support for SIP and XMPP audio calls). Also, an informative section describes the main properties of call history entries. This specification reflects the consensus reached between the editors from Telefonica and Intel. Features like video call, call recording, specific telephony services (e.g. supplementary services, network and SIM information, etc), fetching/searching call history are left to other specifications, or later development of this specification. The old specifications have been moved to the input_docs folder.