ucs: only initialize when contact list is migrated

commit a58344becf4d0bc0518262492c3b9a79020120c4 changed UCS to always
fully initialize, because we needed it for buddy photos. That reason
went away with commit ce3df80c38e07f8879fb52a15467f5268fcba040.
Fix #263: ADFS fails when user and login name differ

Use authuser also for web ticket ADFS requests, if it is set. This will
fix failing ADFS authentication for users where the SIP user name is
different from the authentication name.
processing the response to presence publish event(SERVICE). For some lync servers, a publish does not trigger a notify. So the only way to update the state version number is to process this response.
srtp: parse encryption key from SDP
srtp: generate encryption key for each stream
srtp: offer encryption key when initiating a call
srtp: implement sipe_backend_media_set_encryption_keys()
notify: store ucPC2PCAVEncryption value form server
srtp: add sipe_backend_media_get_encryption_policy()
media: send encryption SDP attribute based on policy
media: add stream_decryption_keys list to sipe_media_private
media: refactor encryption compatibility check
srtp: negotiate encryption and apply keys to backend
srtp: encryption policies WIP
media: mux RTP and RTCP when using TCP connection

Lync uses a single TCP connection for both components.
media: duplicate TCP candidates
filetransfer: use 'init' callback in sipe_file_transfer

Replaces sipe_core_ft_incoming_init() and sipe_core_ft_outgoing_init()
and the specific callback method is now set by Sipe core depending on
whether incoming or outgoing file transfer is being handled.

Will allow for some code to be shared between legacy OCS file transfer
implementation and the new Lync approach.
filetransfer: use 'cancelled' callback in sipe_file_transfer

Replaces sipe_core_ft_cancel().
filetransfer: use 'deallocate' callback in sipe_file_transfer

Replaces sipe_core_ft_deallocate().
filetransfer: use 'start' callback in sipe_file_transfer

Replaces sipe_core_tftp_incoming_start() and
sipe_core_tftp_outgoing_start().