Support for OSM metadata

[severinmenard]

As commenting on very old open issues may remain unnoticed, I created this fresh new one in order to get an update on this topic.
Is there any plan about implementing the metadata (user, timestamp, etc.)?
Not having the possibility to get the metadata is huge, huge gap for imposm vs osm2pgsql, whose development has recently restarted. I would prefer not have to switch, but we will need to get access to these metadata.

[francois2metz]

Duplicate of #58