Transform http & https imports?

[cspotcode]

Can we use our transpilation fallback to transform http imports? Could be cool: import straight from github or whatever. Node already handles the download.

Things to consider:

• initial support would not typecheck; would require transpileOnly or some module declarations to keep the checker happy
• how to figure out if a URL requires transpilation? File extension? mimetype? Header?
• initial support would not do any resolutions
• would use local tsconfig.json, would not discover tsconfig on remote server