Bugfix: display standard types and forbid deleting for them
Feature test for disabled deleting of standard types
Forbid destroy for standard types
TypesController spec
Added error message for standard types forbidden destroy
Adds spec steps that test destroy functionality for standard types and types in use
Fix errors mentioned in the code review
Code review fixes
Merge pull request #1012 from netfighter/bugfix/3531_type_none_cannot_be_configured