Username is on the connection objet

We're manipulating a Gerrit object not a GerritConnection object.
The username property is found on the Gerrit object.

Change-Id: I9b4c4cc0dacf456c1cb71c3798141ac726b1db71
diff --git a/jeepyb/cmd/manage_projects.py b/jeepyb/cmd/manage_projects.py
index c438f02..53b00f8 100644
--- a/jeepyb/cmd/manage_projects.py
+++ b/jeepyb/cmd/manage_projects.py
@@ -219,9 +219,9 @@
         return GERRIT_SYSTEM_GROUPS[group]
     gerrit.createGroup(group)
     for user in list(gerrit.listMembers(group)):
-        if gerrit.username == user['username']:
+        if gerrit.connection.username == user['username']:
             # Gerrit now adds creating user to groups. We don't want that.
-            gerrit.removeMember(group, gerrit.username)
+            gerrit.removeMember(group, gerrit.connection.username)
             break
     uuid = _get_group_uuid(gerrit, group)
     if uuid: