FS-4303 --resolve

The fix for FS-3577 causes instabilities if multiple listeners are connected it seems. Undoing this change for now until I can figure out the root cause.

In a sofia profile, you can now set the parameter tls-timeout to a
positive integer value which represents the maximum time in seconds
that OpenSSL will keep a TLS session (and its ephemeral keys) alive.

This value is passed to OpenSSL's SSL_CTX_set_timeout(3).

OpenSSL's default value is 300 seconds, but the relevant standard
(RFC 2246) suggests that much longer session lifetimes are
acceptable (it recommends values less than 24 hours).

Longer values can be useful for extending battery life on mobile
devices.
Signed-off-by: Travis Cross <tc@traviscross.com>

FS-4299 --resolve regression from 23f8967c the code was not making sure both endpoints were type 'sofia' and dereferencing dingaling channel into sofia and causing memory corruption

The revision was no longer picking up the last git commit.  Instead,
it was showing the last release.  This commit appends the last git
commit hash to the last release if a git repository is available.
Further, it checks whether there are uncommitted changes in the git
repository and adds an unclean tag to the version if this is the case.

Note that currently this will append the git commit hash even on a
tagged release if built directly from a git repository.  Perhaps this
isn't such a bad thing, but if it turns out not to be desired, I have
an idea on how to squelch this without making unwarranted assumptions
about the remote layout of someone's local repository.

don't segfault after starting sofia, upon xml_open_config lookup failure for the profile from launch_sofia_worker_thread

There are a lot of codecs these days, and some clients offer all of
them.  If we run out of space in this buffer our local SDP will get
silently truncated, which will cause a difficult to diagnose error in
Sofia-SIP.

Thanks to Anthony Minessale.

FS-4293 --resolve

This error was causing us to call generate_m with a buffer length that
was less than the strlen of the buffer we were passing.  The result
was truncated local SDP which would cause sofia to fail if the
truncation was in a particularly bad place.

Thanks to Anthony Minessale for the fix and working with me to
diagnose the issue.

FS-4293 --resolve

This amends commit a6bb4545.

Related to issue FS-4293.

 * fixed bug with remote hello-hash buffer being too small
 * removed unused hello-hash storage in zrtp stream context
 * fixed bug with libzrtp rendered "empty" SAS hash from incoming
   SasRelay packet
 * incremented libzrtp version number to 1.15
Signed-off-by: Travis Cross <tc@traviscross.com>

It's broken too many of my recent builds.  We can add it back in when
things stabilize or perhaps after we get it to swig with a recent
version of swig that we can make part of the clean bootstrap/build
process.