react to aspnet/Hosting#996

[analogrelay]

• Also add more tracing to try and identify what is hanging
• Forward logs from each test to a separate file
• File logging only occurs when ASPNETCORE_TEST_LOG_DIR is set to a value, and that value specifies the root directory to store logs in. Logs are stored in directories for each assembly and test class. (I've run the tests in a directory deeper than the CI uses and made sure that they don't hit MAX_PATH ;))
• I've already updated build configurations to have this variable and to publish the logs as artifacts readable from the build
• Also updated nginx config since it was using a deprecated config option which was a warning, but will soon be an error (/cc @BrennanConroy)

Follow up from aspnet/Hosting#996

[dnfclas]

@anurse, Thanks for having already signed the Contribution License Agreement. Your agreement was validated by .NET Foundation. We will now review your pull request. Thanks, .NET Foundation Pull Request Bot

[analogrelay]

Unfortunately the Travis failure is legitimate and back in Hosting. It's unfortunate we don't really have a test that uses the integration test components cross-plat in Hosting itself. I'm going to make the change there and try to test it out in advance with docker this time ;)