Proposal: compatability with GENI AM API GetVersion

This is a proposal related to google doc issue 11
This should be discussed further.

This adds the (optional) options "geni_api" and "geni_api_versions" to the federation-am-api for servers that wish to be able to redirect GENI AM API clients to the correct URL.

It also describes how GENI AM API servers can refer to the federation-am-api.