Stripe - Update Tables

[jazsmi]

This PR:

• Adds the payout_transactions and disputes tables (Add payout_transactions singer-io/tap-stripe#23, Add disputes stream singer-io/tap-stripe#29)
• Updates the Primary Key for invoice_line_items to id:invoice (Invoice Line Items should use a composite PK singer-io/tap-stripe#19)
• Adds the tiers attributes for plans to the plans and subscriptions.plans tables (Fix plan schema singer-io/tap-stripe#16)

[erinkcochran87]

Just one change on the invoice_line_items table. The change on the tap was to add another field (invoice) to the table's Primary Key, making it a composite of id and invoice.