Address deprecation of setting and special-case Rack adapter config.
Resolve deprecations in dispatcher spec.
Fix failing specs and deprecations in response_spec.
Fix errors and deprecations in adapter_spec
Resolve errors and deprecations in trace fsm spec.
Fix deprecation warnings in flow_spec
Fix deprecation warnings in trace_spec
Resolve deprecation warnings in events_spec
Resolve deprecation warnings in helpers_spec
Resolve deprecation warnings in application_spec
Resolve deprecation warnings in adapter_lint