Assign default add patch set permission on refs/for/*

By default each user should be able to add patch sets on all open changes.
We have created a new permission to lock changes, such that only
the change owner or a specific group can add new patchsets to exisitng
changes.

project.config

diff --git a/project.config b/project.config
index 2cbaef9..51e180f 100644
--- a/project.config
+++ b/project.config
@@ -56,3 +56,5 @@
 	value =  0 No score
 	value = +1 Looks good to me, but someone else must approve
 	value = +2 Looks good to me, approved
+[access "refs/for/*"]
+	addPatchSet = group Registered Users