CLONE - A teacher can set the maximum size of file which students can upload

Test Pre-requisites: An assignment with File Submissions enabled.
1. Login as a teacher, update the assignment and set the maximum size to 10KB.
2. Login as a student and check that the message "Maximum size for new files: 10KB" is displayed.
3. Try uploading a file bigger than 10KB and check that the message "This file is bigger than the maximum size" is displayed.