docker dev start: fix with long name with hyphen

docker_dev_start.py

@@ -160,7 +160,7 @@
         arg.append('-d %s' % nmspc.database)
     if nmspc.install:
         arg.append('-i %s' % nmspc.database)
-    if nmspc.without-demo:
+    if nmspc.without_demo:
         arg.append('--without-demo %s' % nmspc.database)
 
     # auto detect local ip