Move validator shortcut methods from UploadField to FileField
Merge pull request #3304 from kinglozzer/pulls/filefield-validator-shortcuts

Move validator “shortcut” methods from UploadField to FileField (fixes #3258)
BUG Revert some changes to ManyManyList
BUG Fix incompatibility in Member_GroupList
Fix regressions in merges from 3.1
BUG Fix Security failing on test classes
BUG Fix postgresql compatibility
Clarify sql encoding of table names