Easier viewing of of artefact->file plugin config (Bug #1326160)

As we add more config settings to the artefact file plugin it is
easier to find things when we load the config page with all the fieldsets
closed to begin with (like what we do in site config page).

Made the form/page look more like site settings page

Change-Id: I7e6af09d0158644f1d270c602fee83d80c9732fe
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
Merge "Easier viewing of of artefact->file plugin config (Bug #1326160)"