Use real RSS url.
Allow empty image in news import.
Validate dates for event.
Allow empty semester value for a class.
Work on media gallery validation.
Avoid apllying multiple 'isNotEmpty' validators.
Fix for event dates validation.
Remove date end for news.
Pass the value of the field if type is integer.
Allow import of presentation with no date.
Improve validation error messages.
Fix comments.
Merge pull request #6386 from openscholar/6054-fixes-3.14

Fixing import validation of CSV content.