Added DateTimeNormalizer, use W3C format for DateTime Form elements
Remove unused use statement
Implement feedback
Fixes
Added some tests
Updated docbloc
Further feedback
Added check for DateTime value
Update tests for Exception
Merge pull request #3632 from davidwindell/zf3617

New DateTimeFormatter Filter (#3617)
[#3632] throw previous exception

- Incorporate feedback from @marc-mabe
- Also: use $e as exception (for consistency)
Merge branch 'feature/3632' into develop

Close #3632