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>
Signed-off-by: Michael Maximilien <maxim@us.ibm.com>