The ".../packages" endpoints for mirror, local repos and snapshots all
share the same syntax for querying. However the "/api/packages" endpoint
doesn't match this. Adjust that to allow for a bit more consistency and
allow querying the full package database.
The current endpoint functionality "/packages/:name" is kept intact and
can be used the same as now
Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>
