Fixes in sequential branching

1. If branch is not started yet - we should just ignore canceling it.
2. If proxy is canceled - it should remove all pending (not started)
branches as well. Otherwise they would execute upon receing 487 on
INVITE
Log the SIP message which caused error

If during processing SIP messages an exception occurred, we should log
the SIP message causing the error for better troubleshooting.
Ability to skip NAPTR in RFC3263

For environment where it's known that there is no NAPTR records,
RFC3263 can be optionally relaxed to do not query NAPTR and proceed
with SRV lookup directly.
Proper weight/priority sorting of SRV records in RFC3263 resolver

For case when multiple SRV records with same priority exist selection
among them should honor weight (not jsut sort by weight, but select
records randomly according to given weight).
Typos

Fixed typos
Merge branch 'talkatone-master'