Release dataproc 0.4.0 (#8195)
Release dataproc 0.4.0 (#8195)

* Release 0.4.0

* removing an unused section

tseaver/google-cloud-python,tseaver/google-cloud-python,tswast/google-cloud-python,tseaver/google-cloud-python,GoogleCloudPlatform/gcloud-python,googleapis/google-cloud-python,tswast/google-cloud-python,tswast/google-cloud-python,GoogleCloudPlatform/gcloud-python,googleapis/google-cloud-python