gluon-core: add gluon-reconfigure script

Not useful by itself except for testing; will be used for multi-domain
support.

[Matthias Schiffer: rename script, use for initial configuration]

package/gluon-core/files/etc/uci-defaults/zzz-gluon-upgrade

@@ -1,5 +1,5 @@
 #!/bin/sh
 
-for script in /lib/gluon/upgrade/*; do
-	"$script"
-done
+gluon-reconfigure
+
+exit 0

package/gluon-core/files/usr/bin/gluon-reconfigure

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+cd /lib/gluon/upgrade || exit 1
+
+err=0
+
+for script in *; do
+	echo "Configuring: ${script}"
+	./"$script" || err=1
+done
+
+if [ $err -eq 1 ]; then
+	echo 'One or more upgrade scripts failed. Please review the above error messages.'
+	exit 1
+fi
+
+exit 0