Revert "started work on 'optimizing' the unloading process, where we only unload plants that have changed, not completely tested yet..."

This reverts commit dccc254795390a9286cc85d564864b837a818d68.
Added code to the convert_sqlite_to_mysql_rb.py to detect if there are existing plant/chunk tables, and ask the user if they want to DROP them, and also fixed a bug where i was not dividing the date field by 1000 (i was dividing the growth field, i hate numbered indexes....)