Quoting test of $create_options in borg handler

The check for the string length in the condition for appending the $create_options fails because it isn't a string. Fixed with quoting the variable.

Change-Id: I6bdacb81f25cf924dc61e3aa6f4b8ebfbe09da65
Signed-Off-By: Emil Breiner <emil.breiner@krumedia.com>

handlers/borg.in

@@ -140,7 +140,7 @@ if [ ! -z $bwlimit ]; then
    execstr="${execstr} --remote-ratelimit=${bwlimit}"
 fi
 
-if [ ! -z $create_options ]; then
+if [ ! -z "$create_options" ]; then
    execstr="${execstr} ${create_options}"
 fi