Make a few small tweaks/suggestions

- Switch from Net::HTTP to Faraday
- Add `find_bet` before action to BetStepsController
- Swap `class << self` for preferred `def self.methodname`
- Better error definition in BetsController
Faraday is the way to go for all HTTP requests. Right now, it would still use Net::HTTP as an adapter, but switching that out is as easy as changing line 19. For example, if we ever wanted to start making multiple requests at the same time, it'd just be a matter of changing the adapter to Typhoeus. No other code needs to change.