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
I didn't realize Faraday was good for all situations. My understanding was that Faraday is great if you want to insert middleware into the request/response cycle (e.g. when building an API wrapper). In this case, I thought Net::HTTP was ok to use, but I realize the flexibility Faraday brings.

Side note: I had a similar discussion at work the other day. I implemented a POST using HTTParty, so I'll probably switch it to Faraday next week.