Configure gorouter to use system DNS resolver
Configure gorouter to use system DNS resolver

The default Go stub DNS resolver is unable to handle certain DNS
responses since DNS extensions are not implemented.

[#119964953]

Signed-off-by: Edwin Xie <6bc24e9c160281972837d9e13287696d26612564@pivotal.io>

cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release