to_python is not implemented for types columns.Type and columns.Date in CQLEngine

This was discovered as part PYTHON-505. The tests failing due to this are this, this and this, right now they are in the python-505 branch

columns.Date and columns.Time don't have a to_python method defined.

A possible solution for columns.Date is:

and for columns.Time:

but we should consider I think using validate as done in other columns.