Accept collections in producer.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>
Remove hardcoded link to configuration files.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>
add example files for gatherer and catter.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>
Logging and argparsing in catter.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>