RFC 2976 INFO method. Dialog state is not modified, added sending API to
nksip_uac.erl and a corresponding callback to nksip_sipapp.erl. Other than
keeping the dialog's state, the handling is identical to BYE method.
Merge branch 'rfc2976_info' of git://github.com/nkrylov/nksip into rfc2976_INFO

Adaptation to new API and doc updates
nksip_uac: accept only dialog spec for only-dialog methods
Accept info callbacks
New method INFO tests
Contact generation with SIPS uri in URI or Route
Via generation change

According to RFC3261, each UAC transaction attempt uses a different Via's branch
Minor update
REGISTER updates

- Allow registering non-sips Contact with sips From
- Allow different From and To in automatic behavior (SipApp must detect it if necessary)
- Add Contact's scheme to the index used to update stored contacts
- Modify tests and add test for tel:… Contact
Updated register_test
Merge branch 'master' into v0.3
Changes in SIPS selection in Contact generation
Modified nksip_transport_uas:resend_response/3

If the response has not been sent, performs a normal send
Updated Travis
Reply utilities rework
Minor updates
Minor change
Minor change
New SIP location server

New SIP DNS location and cache server, fully supporting RFC3263, RFC2782 and RFC2915
Doc minor updates