Override content disposition with provided filename

[bolek]

When provided to store/1
%{filename: "some file.png", remote_path: "https://example.com/file"}
and the remote_path returns a content disposition header,
we get a unhandled CaseClause exception

example:

elixir

** (CaseClauseError) no case clause matching: {:ok, "/var/folders/mw/xdbkgz2n1fdgd75384n7mrr40000gn/T/WM2DEEDR55E4VNIPURIBLPMKV4DBLKFD.png", "image three.png"}

This PR fixes the above, by adding a case clause. It will use the provided filename rather than the filename
returned in the content disposition header.