Description of problem:
when using rhc-ctl-domain -u to update non-existing ssh key name, it will add the ssh key name to this domain

Version-Release number of selected component (if applicable):
rhc-broker-0.84.37-1.el6_2.noarch 

How reproducible:
always

Steps to Reproduce:
1.generate secondary ssh key via ssh-keygen
2.update ssh key with non-existing key name
# rhc-ctl-domain -r ethkeyname -k ~/.ssh/libra_id_rsa_new.pub
3.
  
Actual results:
the non-existing key name will be added to the domain directly.

Expected results:
should fail and error message should inform user the corrective action


Additional info:

[root@localhost .ssh]# rhc-ctl-domain -u keynonexist -k libra_id_rsa_2.pub -d
Password: 
Submitting form:
ssh: AAAAB3NzaC1yc2EAAAABIwAAAQEAp4c3Wz5tRToKRtCYYmSQhnUo/SlW05b7UBiEY8KHqfI6OhuSLaX3zZd0YEuVSKaRC5z3t7lyzo8XjrjAquu3EV1cMVexODQJKONqz+voBU5+Bsi3104IoswJzmttlVeEp6tTClDOtXM/S2/8N6pdFICyrwExIyABJ3DFRb4K7hzTmp21Ci90YsAw+vQW9Vl7vMqzKaVomkNXDh8Ya8UeoUiA/0aC5GdADNAWjgIVmxxUDQL47rB2nFmxBzFLSvkM+svBTuZ+dx05DcYBQ95kpryj6UTSW3xwbfECqeJ4ph3GKh26evC6ugyPAcYEp5s4MBVC7hFkNqS40RP3LYUv8Q==
action: update-key
key_name: keynonexist
key_type: ssh-rsa
rhlogin: bmeng+1
Contacting https://ec2-107-21-79-175.compute-1.amazonaws.com
Response from server:
DEBUG:


Exit Code: 0
broker_c: namespacerhloginsshapp_uuiddebugaltercartridgecart_typeactionapp_nameapi
api_c: placeholder
API version:    1.1.1
Broker version: 1.1.1
Success