[db] Fixes error where _get_column_creation_text does not properly accept columns as tuples when a key is defined.

Signed-off-by: Eldon McGuinness <eldon.mcguinness@gmail.com>
[db] Updated Table.__init__ to account for multiple columns that are defined as tuples.

Signed-off-by: Eldon McGuinness <eldon.mcguinness@gmail.com>