Merge branch 'osupdate-redhat' into 'develop'

Do OS-Update - Redhat family

See merge request ispconfig/ispconfig3!1356

server/mods-available/remoteaction_core_module.inc.php

@@ -180,9 +180,8 @@ class remoteaction_core_module {
 		if(file_exists('/etc/gentoo-release')) {
 			exec("glsa-check -f --nocolor affected");
 		} elseif(file_exists('/etc/redhat-release')) {
-			exec("dnf -y update");
-		}
-		else {
+			exec("which dnf &> /dev/null && dnf -y update || yum -y update");
+		} else {
 			exec("apt-get update");
 			exec("apt-get -y upgrade");
 		}

server/plugins-available/software_update_plugin.inc.php

@@ -289,6 +289,11 @@ class software_update_plugin {
 			$app->log('Execeuted Debian / Ubuntu update', LOGLEVEL_DEBUG);
 		}
 
+		//** Redhat, CentOS, Fedora
+		if(file_exists('/etc/redhat-release')) {
+			exec("which dnf &> /dev/null && dnf -y update || yum -y update");
+		}
+
 		//** Gentoo Linux
 		if(file_exists('/etc/gentoo-release')) {
 			exec("glsa-check -f --nocolor affected");