restapi : Throw error when the value of url 'max' param is not convertible to int (#958726)

List command with --max does not throw error message
when the value passed is not a valid integer

Change-Id: I9f2ae614f7119a2d6c0cf832cc82f305a21b63a7
Bug-Url: https://bugzilla.redhat.com/958726
Signed-off-by: Ravi Nori <rnori@redhat.com>