Enable owners plugin

Allow anyone in the all-maintainers group to approve(+2) any change.
Enable the owners plugin on all repositories, and require approval from
at least one owner of all affected files.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/project.config b/project.config
index 0af3201..9912eae 100644
--- a/project.config
+++ b/project.config
@@ -4,6 +4,7 @@
 	action = rebase if necessary
 [access "refs/heads/*"]
 	submit = group Registered Users
+	label-Code-Review = -2..+2 group github/openbmc/all-maintainers
 [access "refs/meta/config"]
 	label-Code-Review = -1..+1 group Registered Users
 	label-Verified = -1..+1 group Administrators