Description of problem:

running: 
   'oc set triggers dc/jenkins --containers jenkins --from-image='openshift/my-jenkins:verified-1.1' -n my-test-project'
does unexpectedly set namespace of image, while expected is to limit the search in which dc this get applied to.

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

openshift v3.5.5.31.36
kubernetes v1.5.2+43a9be4

How reproducible:


Steps to Reproduce:
1. create project 'myproject' and deploy some app, so that you have a dc
2. run a 'oc set triggers' including parameter '-n myproject'
3.

Actual results:
dc will contain:
    triggers:
    - type: ConfigChange
    - imageChangeParams:
        automatic: true
        containerNames:
        - jenkins
        from:
          kind: ImageStreamTag
          name: my-jenkins:verified-1.1
          namespace: my-test-project
      type: ImageChange


Expected results:
dc should look like:
    triggers:
    - type: ConfigChange
    - imageChangeParams:
        automatic: true
        containerNames:
        - jenkins
        from:
          kind: ImageStreamTag
          name: my-jenkins:verified-1.1
          namespace: openshift
      type: ImageChange

Additional info:

'oc set triggers --help' doesn't give any hint that '-n' is applied to image and not to the object as usual.