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
[This explains the format Logan defined above](http://blog.rubybestpractices.com/posts/gregory/anonymous_class_hacks.html)