Add a future for casting complex numbers involving -0.0i to string

The case that is meant to handle this in the _cast function is not executing so
the cast is not handled correctly.
Add a .bad file for complexCastToString test
Merge pull request #141 from daviditen/newFutures

Add a future for casting complex numbers involving -0.0i to string

The case that is meant to handle this in the _cast function is not executing so
the cast is not handled correctly.