adding fixes to support older versions of mongo (and pymongo) as well as new versions

database/mongodb_user

@@ -64,7 +64,7 @@ options:
         version_added: "1.3"
         description:
             - The database user roles valid values are one or more of the following: "read", "readWrite", "dbAdmin", "userAdmin", "clusterAdmin", "readAnyDatabase", "readWriteAnyDatabase", "userAdminAnyDatabase", "dbAdminAnyDatabase"
-            - This param requires mongodb 2.4+
+            - This param requires mongodb 2.4+ and pymongo 2.5+
         required: false
         default: "readWrite"
     state:
@@ -88,7 +88,7 @@ EXAMPLES = '''
 # Delete 'burgers' database user with name 'bob'.
 - mongodb_user: database=burgers name=bob state=absent
 
-# Define more users with various specific roles (default is 'readWrite')
+# Define more users with various specific roles (if not defined, no roles is assigned, and the user will be added via pre mongo 2.2 style)
 - mongodb_user: database=burgers name=ben password=12345 roles='read' state=present
 - mongodb_user: database=burgers name=jim password=12345 roles='readWrite,dbAdmin,userAdmin' state=present
 - mongodb_user: database=burgers name=joe password=12345 roles='readWriteAnyDatabase' state=present
@@ -113,10 +113,16 @@ else:
 # MongoDB module specific support methods.
 #
 
-def user_add(client, db_name, user, password, roles):
+def user_add(module, client, db_name, user, password, roles):
     try:
       db = client[db_name]
+      if roles is None:
+        db.add_user(user, password, False)
+      else:
+        try:
           db.add_user(user, password, None, roles=roles)
+        except:
+          module.fail_json(msg='"problem adding user; you must be on mongodb 2.4+ and pymongo 2.5+ to use the roles param"')
     except OperationFailure:
       return False
 
@@ -162,7 +168,7 @@ def main():
             database=dict(required=True, aliases=['db']),
             user=dict(required=True, aliases=['name']),
             password=dict(aliases=['pass']),
-            roles=dict(default=['readWrite'], type='list'),
+            roles=dict(default=None, type='list'),
             state=dict(default='present', choices=['absent', 'present']),
         )
     )
@@ -199,7 +205,7 @@ def main():
     if state == 'present':
         if password is None:
             module.fail_json(msg='password parameter required when adding a user')
-        if user_add(client, db_name, user, password, roles) is not True:
+        if user_add(module, client, db_name, user, password, roles) is not True:
             module.fail_json(msg='Unable to add or update user, check login_user and login_password are correct and that this user has access to the admin collection')
     elif state == 'absent':
         if user_remove(client, db_name, user) is not True: