Don't enforce available locales.

See this article for more info:
http://stackoverflow.com/questions/20361428/rails-i18n-validation-deprecation-warning
Create the DataSet model.
Remove the stupid concerns/ dirs.
Update the DataSet model with fields for "buy" and "sell" prices.
Update the "cad_to_usd_rate_cents" field to be able to store 4 decimal digits.
Add DataSet#cad_to_usd_rate .
Install the MtGox, Bitstamp, and BTC-E gems.
Create services for accessing the ticker for CaVirtEx, CampBX, and Coinbase.