Update schema.rb

[vaihtovirta]

Column names from production:

irb(main):003:0> Transaction.column_names
=> ["id", "transaction_type", "price", "amount", "coin_id", "user_id", "created_at", "updated_at", "btc_price", "transaction_date", "is_expired"]
irb(main):006:0> Conversion.column_names
=> ["id", "receive_coin_id", "sending_coin_id", "user_id", "amount", "rate", "max_amount", "min_amount", "return_address", "withdrawal_address", "deposit_address", "raw_data", "status", "created_at", "updated_at"]