Issue #340 : Remote links for single file: HTTP (fsnip, etc.) and Gist

Support for any http-source download link.
Gist also suported multiple files so it is separte from any http-source.


I'm complaining not about the name for the file you find out by splitting the url. Although why do we assume `.fs` as default file ending being referenced?
My initial complain was about different resource could be delivered for the altered url.
`http://example/item != http://example/item/`