Description of problem:

When trying to add brick and specifying cluster only I get the following error: 
'Cluster' object has no attribute 'bricks'
I would change this error to be more meaningful : 
e.g glustervolume parameter is mandatory. 


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
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Actual results:


Expected results:


Additional info:

[RHEVM shell (connected)]# list clusters 

id         : 99408929-82cf-4dc7-a532-9d998063fa95
name       : Default
description: The default server cluster

id         : 300664d6-d0a6-4065-95ab-e1c43a484384
name       : test

id         : 60fb9cb7-4945-417a-9f68-e7cbb141e4c5
name       : test3

[RHEVM shell (connected)]# add brick --cluster-identifier 300664d6-d0a6-4065-95ab-e1c43a484384

unknown error: 'Cluster' object has no attribute 'bricks'

[RHEVM shell (connected)]#