Cleanup the configuration handling in http_SUITE
Enable Autobahn Test Suite by default

Includes a variety of small changes that are a first step to
improving the test system heavily.
Silence expected test error reports from the console output

The errors are still logged by common_test to the report it creates.
The process that is going to crash has to call cowboy_error_h:ignore/3
with the MFA where the crash is expected to occur for it to be ignored.
Gun retry failures are also ignored. Only unexpected crashes are printed.