add purchasing tracker

[denizsivas]

add a 4th and 5th databases with an interface for tracking the goods user wants to buy

initialize db as, ------------------- product db

• id
• product name
• link
• date added -------------------- price db
• date
• price (the price column needs to be relational with the product id)

[denizsivas]

https://stackoverflow.com/questions/25375179/one-to-many-flask-sqlalchemy for referencing