install and init script for el5

Fixes #186
Closes #203

scripts/init.sh

 #! /usr/bin/env bash
 
+# chkconfig: 2345 99 01
+# description: Telegraf daemon
+
 ### BEGIN INIT INFO
 # Provides:          telegraf
 # Required-Start:    $all

scripts/package.sh

@@ -160,7 +160,14 @@ rm -f $INSTALL_ROOT_DIR/init.sh
 ln -sfn $INSTALL_ROOT_DIR/versions/$version/telegraf $INSTALL_ROOT_DIR/telegraf
 
 if ! id telegraf >/dev/null 2>&1; then
+    useradd --help 2>&1| grep -- --system > /dev/null 2>&1
+    old_useradd=\$?
+    if [[ \$old_useradd == 0 ]]
+    then
         useradd --system -U -M telegraf
+    else
+        groupadd telegraf && useradd -M -g telegraf telegraf
+    fi
 fi
 
 # Systemd