Adding 'self.depends' option in root.py

This option will be used by WoK to determine the dependencies
of the plug-ins. The change made is harmless - the  patch does
not need the WoK changes to be upstream beforehand.

Signed-off-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>

root.py

@@ -73,6 +73,8 @@ def __init__(self, wok_options):
             }
         }
 
+        self.depends = ['gingerbase']
+
         # Some paths or URI's present in the objectstore have changed after
         # Kimchi 2.0.0 release. Check here if an upgrade in the schema and data
         # are necessary.