Remove framework dependencies on deprecated methods

Addressing this issue:
https://github.com/codeguy/Slim/issues/924

I didn't know what to do the tests, but I guessed that we wanted to update them where they still applied, and keep the ones that test specific behavior for the deprecated function until it gets removed.

https://github.com/ecoreng/Slim/blob/fw-remove-dep-depr/tests/ViewTest.php#L144
https://github.com/ecoreng/Slim/blob/fw-remove-dep-depr/tests/ViewTest.php#L100