Issue #4172 - Added tests for add/remove sequence in Zend\Form

Related with the issue #4172

Separated pull request as asked in https://github.com/zendframework/zf2/pull/4185#issuecomment-16129242 containing tests for the form class, that is affected by this bug.

This test will fail until https://github.com/zendframework/zf2/pull/4199 is merged as it fixes this bug.