Add dotnet new-relic agent support

[pivotal-david-osullivan]

Summary

Updates the new-relic action to support a new 'type' for the dotnet agent. This agent is hosted in a different way then the php agent and so the URI and regex is different: https://download.newrelic.com/dot_net_agent/

Use Cases

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).