Adding assert for type and tag

Implements `assertWrappedElement` to check for correct wrapped element in typified elements.

Closes #53 
I see now. You created failing attribute test in the test case for button element. And now when button element checks have become more complex the failing attribute test must become as well.

This proves that failing attribute test should be created for fake fixture element and not be based on existing element. Then we wouldn't have this problem in first place.