Clean up initialization code

[Matt Perpick (clutchski)]

• tracing param is now enable_tracing so it's more clear
• if you don't call init, we'll init under the hood when you run an eval using env var config. before eval run would throw a "no state erorr" if you didn't explicitly call init
• remove logged_in param that didn't need to be public
• move auth and tracing setup inside of state.new