test.ini: enable memcache server
Fix: cannot change the badge thumbnail image (cache invalidation not working right)
added FileUpload and ImageFileUpload Validator
pep8
set default ValidImageFileUpload max size to 5MB
Thumnail Badge image upload: check valid image type and max size
Merge branch 'feature-thumbnail_badges_#191_hierarchical_badge_#95' of https://github.com/liqd/adhocracy into feature-thumbnail_badges_#191_hierarchical_badge_#95