Add light box assets

Issue #4
Return big image url

Issue #4
Use the fancybox in defect view

Issue #4
Improve fancybox styles

Issue #4
Merge branch 'add-lightbox' into add-lightbox-merge

Conflicts:
	citydefects/static/js/defects.js
Merge pull request #6 from mociepka/add-lightbox-merge

Add lightbox merge