Edit DB renamed to Seed DB, needs test and merge

Hi,

I've just spent an hour on renaming editdb to seeddb, as described in the https://blueprints.launchpad.net/nav/+spec/rename-editdb blueprint. The code is now running at navdev and is available at navdev:~jodal/nav/jodal/rename-editdb.

1) Morten and Vidar: could you please poke around at navdev a bit to test that everything seems okay?

2) Morten: could you please merge the branch or give me a green signal for merging before other branches diverges too much? I've changed code in large parts of NAV (including the infamous nav.django.urls) to accomplish the renaming, and would very much like to win the merge war by merging first ;-)

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