Store the uploader of documents
make uploaded_by_user a noneditable field on images, rather than excluding it from specific forms
add document permissions and require add_document permission to access the documents area
remove Documents from menu when user has no add_document permission
enforce permissions on editing documents uploaded by other people (requires change_document permission; add_document permission allows editing/deleting your own documents)
Limit contents of documents index according to permissions
Suppress the 'upload' tab of the document chooser if the user has no add_document permission
Merge branch 'feature/documentpermission' into develop