feature(server): Add ability to set displayed log level from an environment variable.
feature(server): Add ability to set displayed log level from an environment variable.

* Use the `LOG_LEVEL` environment variable.

jamonation/fxa-auth-server,dannycoates/picl-idp,chilts/fxa-auth-server,mozilla/fxa-auth-server,dannycoates/picl-idp,jrgm/fxa-auth-server,chilts/fxa-auth-server,shane-tomlinson/fxa-auth-server,jrgm/fxa-auth-server,eoger/fxa-auth-server,mozilla/fxa-auth-server,shane-tomlinson/fxa-auth-server,chilts/fxa-auth-server,eoger/fxa-auth-server,mozilla/fxa-auth-server,jamonation/fxa-auth-server,dannycoates/picl-idp,shane-tomlinson/fxa-auth-server,jamonation/fxa-auth-server,TDA/fxa-auth-server,shane-tomlinson/fxa-auth-server,TDA/fxa-auth-server,TDA/fxa-auth-server,mozilla/fxa-auth-server,eoger/fxa-auth-server,jrgm/fxa-auth-server,eoger/fxa-auth-server,chilts/fxa-auth-server,jamonation/fxa-auth-server,TDA/fxa-auth-server,dannycoates/picl-idp,jrgm/fxa-auth-server