Add basic tests for "add --no-copy".
Add basic tests for "add --no-copy".

Note that as per issue #2259 content is not verified for local
retrieval so changing the file content will not always be detected.

License: MIT
Signed-off-by: Kevin Atkinson <13fbd79c3d390e5d6585a21e11ff5ec1970cff0c@kevina.org>

ipfs-filestore/go-ipfs,ipfs-filestore/go-ipfs,ipfs-filestore/go-ipfs