utils.find_resource does not catch right exception

Currently, utils.find_resource catch NotFound exception defined in
openstackclient. However, different client libraries raise different
exceptions defined in thire own library.

Change-Id: Idc40428e30e59f71dbdbfa0555c0066fddc441c2
Closes-Bug: #1371924
Merge "utils.find_resource does not catch right exception"