Convert integration tests to run against both Akka HTTP and Netty

Not all tests are currently working with Akka HTTP. Failing tests
are marked with pendingUntilAkkaHttpFixed or
skipUntilAkkaHttpFixed so that they don't cause test failures.
Merge pull request #3744 from richdougherty/akka-http-integration-tests

Convert integration tests to run against both Akka HTTP and Netty