Confirm when leaving photo upload page

The browser will now ask for confirmation when a user tries to leave
whilst still uploading photos.
Bugfixes for exit confirmation
Remove debug code
Ensure tile photos are full width

Forcibly stretch oddly shaped photos (particularly tall ones)
to be the width of the container on the frontend of the site.
Store logs in redis during processing
Merge pull request #193 from robotmay/confirm-on-leave

Ask for confirmation when leaving page whilst uploading
Merge pull request #194 from robotmay/stretch-tile-photos

Ensure photo tiles are the correct width
Fix for expansion specs
Merge pull request #196 from robotmay/photo-logging

Store logs on photos during processing for debugging
Update README with updated build status image
Merge remote-tracking branch 'upstream/master'