Handle Seahorse::Client::NetworkingError exception
Handle Seahorse::Client::NetworkingError exception

- Fixes `<Seahorse::Client::NetworkingError: getaddrinfo: Name or service not known>`
  on linux and on OSX the error message is more informative

[#135963847](https://www.pivotaltracker.com/story/show/135963847)

Signed-off-by: Lyle Franklin <31e283733c7a4b3b6cb03b95ab535671c2112bbe@pivotal.io>
Signed-off-by: Chris Dutra <7eb54fc324f04033595eb420f2ee7c112fb7259e@pivotal.io>

cloudfoundry-incubator/bosh-aws-cpi-release,cloudfoundry-incubator/bosh-aws-cpi-release,cloudfoundry-incubator/bosh-aws-cpi-release