Fix travis rake task to not specify go_agent

Signed-off-by: Phan Le <ple@pivotallabs.com>
New Trusty OS Image
New Lucid OS Image
Support specifying director port 443

Previously, this would be dropped by the CLI, and replaced with the default
port of 25555. This is a rewrite of the following pull request:
https://github.com/cloudfoundry/bosh/pull/588

Signed-off-by: Kris Hicks <krishicks@gmail.com>