Merge pull request #672 in FS/freeswitch from ~WT123/freeswitch:bugfix/FS-8757-fix-variable-and-header-expansion-buffer-overflow to v1.4

* commit '28da36e3':
  Buffer overflow in switch_channel_expand_variables_check and switch_event_expand_headers_check fixed (FS-8757)

Buffer overflow in switch_channel_expand_variables_check and switch_event_expand_headers_check fixed (FS-8757)

FS-8708 [mod_rayo] fix example configuration to map to correct DETECTED_TONE event from spandsp_start_tone_detect

FS-8619 [mod_rayo] reply with conflict stanza error if bind is attempted with duplicate JID.  Improve error handling when 'ready' callback fails.

Various functions exposed via lua do not check their parameters for null
causing freeswitch to segfault.

This change adds checking for null parameters and returns an error
instead of segfaulting.

FS-8160 Additional vulnerability in json parsing malformed utf encoded chars discovered by Brian Martin - Tenable Security Response CVE-2015-7392

script calling session:getVariable() with a null variable
name will cause FreeSWITCH to segfault.

This change checks whether varname parameter to
switch_channel_get_variable_dup is non-NULL.

* commit 'aaddce34':
  FS-8308 need to double encode if urlencoding json that is already encoded

FS-8370 [mod_rayo] found another place in <prompt> where a message was freed after being queued for delivery. This resulted in a freed object being serialized, crashing FS.

FS-8166 #resolve [Mute/unmute while shout is playing audio fails because the channel "has a media bug, hard mute not allowed"]

FS-8190: [mod_event_socket] When using nixevent, freeswitch stops sending us certain custom event that were NOT part of the nixevent command

Conflicts:
	src/mod/endpoints/mod_sofia/mod_sofia.c

Conflicts:
	src/mod/endpoints/mod_sofia/mod_sofia.c

In the systemd unit for FS/debian, if the WorkingDirectory is not set
then it defaults to '/'.  This is fine for FS, and is a common and
expected chdir choice for daemons.

We had previously set this to /run/freeswitch.  Due to Debian having
systemd-coredump(8) disabled, this was causing core files to be
written to /run/freeswitch, which is a bad place for them as it's
mounted on tmpfs.

It's better to leave FS as running on '/'.  This will prevent core
files from being written unless the user adjusts `sysctl
kernel.core_pattern`, which is a reasonable thing to expect if the
user wants these files.  Core files can be huge, and having them go
anywhere unexpectedly can be a problem.

When Debian adds the systemd-coredumps support this will all work
nicely and automatically.

ref: http://www.freedesktop.org/software/systemd/man/coredump.conf.html
ref: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=744964

FS-7909

This changes how we create the temporary directory /run/freeswitch
when starting FS with systemd.  The /run directory starts empty after
a system reboot, so we need to ensure this directory is present.

As part of systemd.exec(5), systemd provides a mechanism to
automatically manage these directories under /run and to bind their
lifetime to the lifetime of the process.

This commit moves to using the RuntimeDirectory= mechanism and removes
the obsolete ExecStartPre/mkdir code.

FS-7130

FS-8042, FS-8182: add ping time (in ms) to sip_registrations table, displays as part of the show commands that show registration details, add force_ping=true user var to force options ping on individual registered endpoints

FS-8185: [core] Allow xml preprocessor to expand variables where the resulting value is much longer than the original size

FS-8167 [mod_lua] Fixed a segfault caused by using api:execute or session:execute and not quoting the first argument like api:execute(log, “Second argument”) instead of api:execute(“log”, “Second argument”)