- Add file type validator
- Apply validator to user image
- Save validator class to variable
- Add image validator to news image model field
- Add file size validator
- Enable file size validator on news and user model image fields
- Fix test
These fields were just using the default max lengths of 50 and 200
respectively. Since `title`s can be up to 255 characters, adjusted
slug to be 300.
Increased external URL to be huge as it's not impactful to performance
really and avoids possible future creation issues.
Fixes#773
Part of #343. The news' notifications module was also changed to the user
preferences is honored when sending news emails.
Also exclude migrations from the black check.
