Add 'auto' eauth backend for tests
Move eauth_creds to class-level for reuse
Add tests for the cmd_sync and cmd_async RunnerClient methods
Add runner_async and wheel_async clients to NetapiClient

Also switch from master_call to new public-facing methods.
Added NetapiClient integration tests
Switch NetapiClient to use client_config instead of master_config

We access the Salt master through client interfaces and should use the
correct config when doing so. We should also reuse the already-loaded
opts when instantiating LocalClient().
Use WheelClient instead of the deprecated Wheel