save header

[KaylaCrush]

right now I'm just iterating through the tables in self.tables to save, but since I made self.header a separate thing for some reason it's not being included. That might be good! See issue #52 But the fact that it's not saving is bad, ultimately it does need to be saved.

• [ ] Get the length of the headers table,
• [ ] add that value as a source_id to the new row, and
• [x] return the source_id so it can be added to the other tables.

[KaylaCrush]

Did this using the sql serial function to generate a new id for each tentry to the header table

[KaylaCrush]

done