Do not set "_invalid" in case var_name is empty or unset. While at it,
clear the "foo_invalid" variable before doing anything else when a regex
is passed, this ensures that the variable really reflects the current
run.

Fixes an issue in original FS-7783 feature.

Merge pull request #840 in FS/freeswitch from ~SSINYAGIN/freeswitch:bugfix/FS-5936-esl.pm-not-included-in-debian-packages to master

* commit '2b307a0a':
  FS-5936 respect archlib in libesl-perl because it is different depending on distro

Merge pull request #836 in FS/freeswitch from ~PIOTRGREGOR/freeswitch:feature/FS-9124-avmd-extend-xml-config to master

* commit '9415487a':
  FS-9124 [avmd] Extend XML config

Merge pull request #837 in FS/freeswitch from ~NYSOLUTIONS/freeswitch:bugfix/FS-FS-9070-update-automake-config-files to master

* commit '3779c7d5':
  FS-9070 Update config.sub and config.guess

Add number of continuous streak samples.

Merge pull request #833 in FS/freeswitch from ~SSINYAGIN/freeswitch:bugfix/FS-5936-esl.pm-not-included-in-debian-packages to master

* commit '8e35369c':
  FS-5936 wrong dependency on freeswitch-mod-esl

Older versions of automake created files that were unaware of newer system architectures, tested with Debian 8.4 and Centos 7

Merge pull request #831 in FS/freeswitch from ~SSINYAGIN/freeswitch:bugfix/FS-5936-esl.pm-not-included-in-debian-packages to master

* commit '135d13a0':
  FS-5936 ESL.pm packaged for Debian

Merge pull request #816 in FS/freeswitch from ~FLOKR/freeswitch:feature/FS-9079-adding-new-strategy-to-mod_callcenter to master

* commit '8b42c77c':
  FS-9079: [mod_callcenter] Add ring-progressively strategy

A new strategy is now available through mod_callcenter, which aim
is to provide a mix between top-down and ring-all strategies.

If set to ring-progressively, the strategy will call an agent, and
then a second agent, and then a third agent, without cancelling
previous calls.

The delay between each call is 10 sec by default, but it can be
changed using the queue variable ring-progressively-delay.

Merge pull request #691 in FS/freeswitch from ~RAJESH.VAYA/freeswitch:feature/mod_callcenter-json-api to master

* commit '23e53df7':
  FS-8799 [mod_callcenter] Add JSON API interface for mod_callcenter

Merge pull request #829 in FS/freeswitch from ~PIOTRGREGOR/freeswitch:bugfix/FS-9117-avmd-build-fails-on-windows to master

* commit 'f476e23c':
  FS-9117 [avmd] #fix build on Windows

Merge in Ubuntu Packaging changes

* commit '7375ad9e':
  FS-9081 [Ubuntu Packaging] WIP Patches to build system and configure to allow FS to build on 14.04
  Revert "FS-9081 to build all modules for trusty needs the universe components"
  Revert "FS-9081 Correction to e8f83d05"

This reverts commit e8f83d05.

This reverts commit 1b9fda72.

Merge pull request #824 in FS/freeswitch from ~PIOTRGREGOR/freeswitch:feature/FS-9011-avmd-add-configuration-file to master

* commit 'bf140e9b':
  FS-9011 [avmd] Add XML config

This is a generated file that was added by commit:

    commit 77f52bb6
    "FS-7928 FS-7618 systemd and package build improvements"

We were missing mod_smpp; mod_json_cdr needed to be placed differently
in the file such that it matches the output of the automated generator
we use to check the completeness of this file.

Add XML configuration file.
Bind reloadxml callback.
Add safe parsers of user's input.
Add show/set/load/reload API commands.