Catch InvalidOperation in collection

Because InvalidOperation is not caught in Collection,
when raise InvalidOperation, server 500 error occurs.
Make collection post catch this exception.

Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Add testcase for InvalidOperation

Create resource with same name shoule raise 400 error
instead of 500 error.
Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Signed-off-by: Adam Litke <agl@linux.vnet.ibm.com>
issue#110: Fix list storage volume for inactive pool

List storage volue with inactive pool raise 400 error.
Also change mock model to comply with libvirt behavior.

Signed-off-by: Shu Ming <shuming@linux.vnet.ibm.com>
Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Signed-off-by: Adam Litke <agl@linux.vnet.ibm.com>