Correct formatting
Add #one_minute to KrakenBitcoinEuro
Reformat update_kraken_bitcoin_euro Rake task
Reset the database before each test
Allow #one_minute test to hit database
Reduce #one_minute test code
Add 'remove_oldest_day_of_data' Rake task

I'm running out of storage on Heroku's development database plan and I'm not interested in data older than a week.