Bug fix empty value check CentOS (#85)

* added CentOS, Fedora, RHEL choices with minimal version check (recommited)

* fixed small typos

* added special option --use-php5-package

* parse options and export new environment variable USE_PHP5_PACKAGE

* added choice between php5* or php7.0* packages (recommited)

* fixed php*-fpm service name and php.ini file path (recommited)

* prepare socket name for nginx to work with php5-fpm or php7.0-fpm (recommited)

* added ppa:ondrej/php5-compat repo

* added dependency ppa:ondrej/php repo and package software-properties-common

* POSIX sh empty value check compatibility

centos/resources/fusionpbx.sh

@@ -22,7 +22,7 @@ wget https://forensics.cert.org/cert-forensics-tools-release-el7.rpm
 rpm -Uvh cert-forensics-tools-release*rpm
 yum -y --enablerepo=forensics install lame
 
-if [ $USE_SYSTEM_MASTER = true ]; then
+if [ .$USE_SYSTEM_MASTER = .true ]; then
 	verbose "Using master"
 	BRANCH=""
 else