Force contributors to define a test by adding it to the create template

A little cheeky but it should help us to maintain higher quality.

Library/Homebrew/cmd/create.rb

@@ -122,6 +122,11 @@ class FormulaCreator
     <% end  %>
         system "make install"
       end
+
+      def test
+        # this will fail we won't accept that, make it test the program works!
+        system "/usr/bin/false"
+      end
     end
     EOS
   end