[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>
[DB] Fix for altering tables when columns are specified as tuples
[DB] Fixed WillieDB._sqlite to actually append found tables to self.tables

This should address issue #334

Signed-off-by: Eldon McGuinness <eldon.mcguinness@gmail.com>
Merge pull request #383 from EldonMcGuinness/db-create-table-errors-on-column-tuples

[DB] SQLite and Tuple Column related errors