Core - make :reporting and :properties categories global

Before 3.0 each plugin defined their own note category, this doesn't
work well, because if you first export to PDF and then to HTML, you have
to change all the categories.

Now plugins will use Category.reporting and Category.property to find
the right notes.

engines/core/app/models/dradis/core/category.rb

@@ -27,6 +27,14 @@ def self.issue
         find_or_create_by(name: 'Issue description')
       end
 
+      def self.properties
+        find_or_create_by(name: 'Project properties')
+      end
+
+      def self.report
+        find_or_create_by(name: 'Report category')
+      end
+
       # -- Instance Methods -----------------------------------------------------
 
       private