fix start script on ubuntu 18.04

fixes #309

compose/bin/start

@@ -20,7 +20,7 @@ function parseYaml {
     if (length($3) > 0) {
       vn=""; for (i=0; i<indent; i++) {vn = (vn)(vname[i])("_")}
       if ("'$2'_" == vn) {
-         print substr($3 ,0 , match($3,":")-1)
+         print substr($3 ,1 , match($3,":")-1)
       }
     }
   }'