Prevent option override

Do not override box/suite specific configuration with global
configuration.

Signed-off-by: Georg Pfuetzenreuter <mail@georg-pfuetzenreuter.net>

scullery.py

@@ -77,6 +77,7 @@ def _config():
         if onemulti in config.sections():
             for option in config.options(onemulti):
                 for collection in configmap[multi]:
+                    if not option in configmap[multi][collection]:
                         configmap[multi][collection][option] = config.get(onemulti, option)
         if multi in ['boxes', 'suites']:
             if not len(lowconf):