[cosmetic] artwork_sizes height and width are now integers in the DB, and displayed with the corresponding unit (closes #14)
[evol] ArtworkStepImage: added helper method to get a thumbnail by size
[fix] work around steps order when done at the same date (considering people would add them in chronological order) using image id
[fix] wrong method call
[evol] an artwork can have multiple materials
[fix] renamed 'technique' into more appropriate name 'artwork_support', and update schema and translations (Closes #4)
[fix] improve password validation #2
[fix] improve password validation
[fix/evol] forgot new files in the previous commits and check admin status to access user management
Initial version