create westminster council so report_new test can run standalone

The test relies on a body for westminster council existing which is
crated in an earlier test if you run the whole test suite. However it's
not present if you run only this test against an empty database so add
it to the list of created bodies.
alter pave url sent to analytics on report completion

In order to allow us to do funnel analysis in google analytics we need
to send a differnt page url when a user completes a report. To do this
we add a report_created=1 to the query string on either the report page
or the report confirmation page for logged in and confirm by email users
respectively.

There's a bit of complication as we don't want to set a session cookie
everywhere as that will break caching so we set a stash variable,
although if the user is logged in this is controlled by a variable in
the flash as there is already a session cookie at this point.

also, removes the code that sends an event upon report completion as
this was no use for funnel analysis.