cli: Bad error message when trying to create a new Role(#908284)

Bad error message when trying to create a new Role without passing
the collection correctly : "unknown error: 'int' object has no
attribute 'split'"

Change-Id: Iba01f4f02c0521332b84e7d5148b0c00c0a70b63
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=908284
Signed-off-by: Ravi Nori <rnori@redhat.com>