dashboard returning 200 status on error

[matthewandrews]

When the dashboard has a Grails runtime exception (e.g. just now due to #94), it is returning a 200 HTTP status code, meaning our external monitoring does not recognise a problem.

[nickdos]

I had a quick look at this but it wasn't trivial, so left it for now. Getting dashboard working was a higher priority due to #94 bug.

NTS: problem is the homepage (index.gsp) is GSP only (no controller code) and everything is loaded via JSON or GSP includes (with their own controller methods). There is already a controller method for index which is tied to a JSON response, which is quite confusing. So this needs to be refactored to a different method/path and a controller method created for the main index.gsp page. I was wrong it is the same method for the GSP.