integ-cli: fix TestImportDisplay & add FileServer

This PR fixes TestImportDisplay. HTTPS handshakes are failing erratically sometimes and that's breaking TestImportDisplay.

This PR moves the download of the file to the Dockerfile and TestImportDisplay simply imports it from a local server which serves files over HTTP.
Would it be better to use a tag or commit here instead of `master`, just in case he moves or renames stuff on us?  He's a nice guy, so it would likely be an inadvertent change not a malicious one, but probably prudent IMO to plan for it happening anyhow. :smile:

(otherwise, LGTM)