Fix BASEDIR & CONFIGFILE eval in init script & param order

Solves #1657

scripts/octoprint.init

@@ -13,7 +13,7 @@
 #                    /etc/default/octoprint.
 ### END INIT INFO
 
-# Author: Sami Olmari
+# Author: Sami Olmari & Gina Häußge
 
 PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
 DESC="OctoPrint Daemon"
@@ -21,9 +21,10 @@ NAME="OctoPrint"
 PKGNAME=octoprint
 PIDFILE=/var/run/$PKGNAME.pid
 SCRIPTNAME=/etc/init.d/$PKGNAME
+DEFAULTS=/etc/default/$PKGNAME
 
 # Read configuration variable file if it is present
-[ -r /etc/default/$PKGNAME ] && . /etc/default/$PKGNAME
+[ -r $DEFAULTS ] && . $DEFAULTS
 
 # Define LSB log_* functions.
 # Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
@@ -55,12 +56,12 @@ then
 fi
 
 COMMAND_ARGS=
-if [ -z "$BASEDIR" ]
+if [ -n "$BASEDIR" ]
 then
     COMMAND_ARGS="--basedir $BASEDIR $COMMAND_ARGS"
 fi
 
-if [ -z "$CONFIGFILE" ]
+if [ -n "$CONFIGFILE" ]
 then
     COMMAND_ARGS="--config $CONFIGFILE $COMMAND_ARGS"
 fi
@@ -91,7 +92,7 @@ do_start()
    if [ $RETVAL != 0 ]; then
        start-stop-daemon --start --background --quiet --pidfile $PIDFILE --make-pidfile \
        --exec $DAEMON --chuid $OCTOPRINT_USER --user $OCTOPRINT_USER --umask $UMASK --nicelevel=$NICELEVEL \
-       -- $COMMAND_ARGS serve $DAEMON_ARGS
+       -- serve $COMMAND_ARGS $DAEMON_ARGS
        RETVAL="$?"
    fi
 }