[Python] Table.drop should support passing a single column

----> 2 data = dataset.drop("Churn") 

/usr/local/lib/python3.7/dist-packages/pyarrow/table.pxi in pyarrow.lib.Table.drop()
    KeyError: "Column 'C' not found"

Also, for consistency, it would probably be good to have a Table.drop_column alias, as all the other methods are named Table.add_column, Table.append_column and Table.set_column