In the initial GitHub Enterprise creation impl, the avatar images for organizations could not be displayed. In order to load those images, the browser must be authenticated against GHE, otherwise the images fail to load with a 302 redirect to the GHE login page.

Scope

• Add an endpoint to the REST API for avatar images that proxies the request to GHE
• Updates "getOrganizations" logic to refer to this endpoint
• Extract data from underlying HTTP session in github-api to pass along the auth session cookie so the requests succeed

Note
I haven't yet been able to validate whether this is possible in github-api. In theory it should be, but it wasn't immediately evident from debugging the code how to get at the underlying http request / response data.