Added continuous and presubmit checks.

[kurtisvg]

Testing changes for presubmit checks to this repo.

[kurtisvg]

@lesv, @frankyn - This PR will allow for presubmit testing of the master branch.

[lesv]

There is another CL that connects with this.

[lesv]

Let me know when everything is working and we can turn CircleCI off for this repo.

[kurtisvg]

@lesv @frankyn This is working, you can disable Circle CI. I will catch up with Frank at some-point so we can compare the Circle CI tests to the Kokoro tests and make sure we aren't missing anything.

[lesv]

It appears to no longer be here, so I'm presuming Frank did it.

[frankyn]

I unassigned it in Circle CI.