Don't run glide install in travis builds.

[jlewi]

• We now check in the vendor directory so there shouldn't be any reason to run
  glide install in our travis builds.

---

This change is 

[jlewi]

@jimexist I just realized that in #232 you removed

- go test -v ./pkg/...

Was that intentional? Does goveralls actually run the tests?

[jlewi]

Looks like it does

$ $GOPATH/bin/goveralls -service=travis-ci -v -package ./pkg/...

?   	github.com/tensorflow/k8s/pkg/controller	[no test files]

=== RUN   TestAddAccelertor

--- PASS: TestAddAccelertor (0.00s)

=== RUN   TestSetDefaults

=== RUN   TestSetDefaults/0

=== RUN   TestSetDefaults/1

=== RUN   TestSetDefaults/2

--- PASS: TestSetDefaults (0.00s)

    --- PASS: TestSetDefaults/0 (0.00s)

    --- PASS: TestSetDefaults/1 (0.00s)

    --- PASS: TestSetDefaults/2 (0.00s)

=== RUN   TestValidate

--- PASS: TestValidate (0.00s)

PASS

coverage: 7.4% of statements in github.com/tensorflow/k8s/pkg/controller, github.com/tensorflow/k8s/pkg/spec, github.com/tensorflow/k8s/pkg/trainer, github.com/tensorflow/k8s/pkg/util, github.com/tensorflow/k8s/pkg/util/k8sutil, github.com/tensorflow/k8s/pkg/util/k8sutil/fake, github.com/tensorflow/k8s/pkg/util/retryutil

ok  	github.com/tensorflow/k8s/pkg/spec	0.106s

[coveralls]

Coverage decreased (-0.1%) to 37.782% when pulling 7a649e8 on jlewi:travis_glide into cb1e053 on tensorflow:master.

[jlewi]

@jimexist can you review this please?

[jimexist]

LGTM

And yes it does, I followed some official docs so I guessed it should work. The report showed that tests are still run everytime.