Added storyID to votes table

Prepares for changing primary key for words to (storyID,wordID);
- Updated create_database.sql
- Changed hash_passwords.py to update_schema.py
- Added schema change code for database structure change
- Modified word.py, story.py and user.py to reflect changes
Added fix_duplicates.py

This file when run once will merge duplicate words once. If child words
contain duplicates, this will need to be run again.