Add support for vagrant proxyconf plugin.

[iconoeugen]

Make sure the openshift service is using the proxy environment configuration that is injected by the vagrant proxyconf plugin.

[jorgemoralespou]

@iconoeugen Can you expand of what would this enable? As far as I know there's also some more configuration that would be required in master-config to properly support proxies, like adding a buildOverrides, so that builds will also use proxies.

If this is an important topic, we can think on adding the whole feature in, but this would be a build time setting (vagrant provisioning) and nothing that could be later changed. Similar to the IP.