Removing ImportError check in Speech client.

[dhermes]

I mentioned this in #2664 and this delivers on it.

We should also get rid of all the instances of this in other packages. LMK what you both think (and @jonparrott I'd be interested in what you think, i.e. importing grpc on GAE)

[theacodes]

It's not ideal for GAE where the gRPC won't be available for some time, but we've already crossed that bridge it seems.

[dhermes]

I'm going to leave this open before merging to let @tseaver weigh in.

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we've already crossed that bridge it seems.

@jonparrott How do you mean?

[theacodes]

we've already crossed that bridge it seems.

There are other locations where grpc is not import checked, right?

[dhermes]

There are other locations where grpc is not import checked, right?

Not that I know of, except a change I made earlier today in speech. Unfortunately the PB definitions are bundled with grpc, so it's tough to parse the Any fields in the operations returned from the API (gRPC or JSON-over-HTTP) without importing the PB types.

[theacodes]

@dhermes Gotcha. In that case I'm fine with this outside of datastore, logging, pubsub, storage, and logging.