Fix _id to uid variable name in MembershipWorks private API

common.py

@@ -52,7 +52,7 @@ def getMembershipworksData(folders, columns):
         print("MembershipWorks User Listing Error: ", r.status_code, r.reason)
         print(r.text)
         sys.exit(1)
-    ids = [user['_id'] for user in r.json()['usr']]
+    ids = [user['uid'] for user in r.json()['usr']]
 
     # get members CSV
     # TODO: maybe can just use previous get instead? would return JSON