Search panel starts hidden.

The search panel is hidden by default using css rather than hiding it
when the page is loaded since there was often a delay on slower
systems like tablets.
Title for group showing available languages is singular.
Moved handlers for 404 and 500 errors into site app.
/ now redirects to /news
Replaced inline form for search panel with a Django form.

Putting the form server-side makes it a lot easier to selectively
hide search fields. This opens up a future path for changing the
fields that are displayed on the current search for example if the
news for islands are being shown it makes little sense to display
search fiels for region or district.
Tidied up javascript.
Added jQuery plugin for setting cookies.