project DOAP not customisable

DOAP is meant to be a detailed description of a project, but the one
that launchpad creates is not user controlled enough.

Specifically:
 - DOAP fields launchpad doesn't know about should be permitted (because
thats the goal of RDF, to be extensible.
 - Its a black box at the moment, about what and how and where stuff
goes into the RDF file.

If I don't control the DOAP file sufficiently well, I'm unlikely to use
Launchpad's DOAP file as the master copy for my project - and at that
point, Launchpad is arguably spreading misinformation if it publishes
the doap record - some users get incensed about that sort of thing; so
it would be nice to be able to turn it off (preferrably by allowing a
'my DOAP is over -> there' field).

- Finally, perhaps I should be able to supply the DOAP file, and have
(where appropriate) launchpad read data from it. reading the summary and
project description from the DOAP file would not be appropriate, because
those fields in launchpad are part of the UI, rather than being purely
about description - they get formatted and linkified.

Allowing user provision of the DOAP file would neatly and immediately
supply all the customisation and control aforementioned. Launchpad could
alert project admins when the DOAP is inconsistent with Launchpads
metadata.

 affects launchpad