The new WebService get_documents() is more efficient in terms of
server resources consumption since it doesn't force the WS engine
to calculate the full result set length, which had little use anyway
in Rigo.
This commit switches entropy.client.services' DocumentList to and
reverse dependencies to use the new WS API. The older WS API will be
kept alive for a while (6 months, roughly).
Fabio Erculiani