New Relic Class Not Found ... I don't even use new relic
It looks like Android Studio switched over to the gradle daemon for faster builds. Unfortunately, this caches parts of the New Relic agent and it's necessary to stop the daemon when you switch to a project without the agent (or a different version. You can accomplish this simply by running:
gradle --stop
You'll also want to clean your project to ensure the classes are rebuilt and dexed.
While this should get you up and running for now, we'll work on a fix for this issue right away and you can expect it in the next version of the agent.