Alert user to scoring competitions

Added an alert to the user's page if there is a scoring
competition which requires the user to submit scores.
Refactor competition.py
Users can always view their own photos.

Update to check that the logged in user is the same as the
photo.user. If so then the photo page can be viewed even
when the competition is still open to submissions.
Disable upload form during upload

Some js which overlays a div on the upload form to stop
users from pressing buttons while the file is uploaded.