Add logging client

[saicheems]

No description provided.

[saicheems]

@tbetbetbe

[dhermes]

General comment: Having things like

self.stub = api_utils.create_stub(
    logging_metrics_pb2.beta_create_MetricsServiceV2_stub,
    service_path,
    port,
    ssl_creds=ssl_creds,
    channel=channel,
    scopes=scopes)

just seems crazy to me. Why is it necessary to have a library to wrap a library? logging_metrics_pb2.beta_create_MetricsServiceV2_stub is supposed to be a useful object for making API calls. So why do we need to wrap it to make another useful object?

The stub also has generated methods exactly like the ones generated here. Why do we need generated methods to cover the already generated methods from gRPC?

---

Aside: It also doesn't make it any easier to use ssl_creds (a pain point of gRPC).

[saicheems]

Thanks for the feedback pass!
Will address everything in the morning

[tbetbetbe]

@anthmgoogle

[saicheems]

Most general style nits addressed - the other issues we are tracking and intend to punt from this PR per offline discussion.
Mainly:

1. Improved documentation (docstrings, argument types, ...)
2. Collapsing the callable

The other quickly solvable issue I'll address in the next PR is making stub a property.

[dhermes]

What is the goal for getting tests to pass here? We already have a fake gRPC for the Bigtable tests, so you might be able to get tests to pass by removing the dependencies that bring in grpcio.

[saicheems]

Fixed setup.py ordering