Add header when posting
Add header when posting

The Search API doesn't respond well when sending JSON in the body of a POST
if the Content-Type header is missing. Add the header when there is a body.

landrito/google-cloud-ruby,googleapis/google-cloud-ruby,landrito/google-cloud-ruby,swcloud/google-cloud-ruby,qingling128/google-cloud-ruby,googleapis/google-cloud-ruby,landrito/google-cloud-ruby,dazuma/google-cloud-ruby,qingling128/google-cloud-ruby,dazuma/google-cloud-ruby,qingling128/google-cloud-ruby,hxiong388/google-cloud-ruby,quartzmo/google-cloud-ruby,swcloud/google-cloud-ruby,blowmage/gcloud-ruby,gwmoura/gcloud-ruby,qingling128/google-cloud-ruby,quartzmo/gcloud-ruby,hxiong388/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,hxiong388/google-cloud-ruby,hxiong388/google-cloud-ruby,CloudVLab/google-cloud-ruby,googleapis/google-cloud-ruby,dazuma/google-cloud-ruby,dazuma/google-cloud-ruby,googleapis/google-cloud-ruby,CloudVLab/google-cloud-ruby,quartzmo/google-cloud-ruby,landrito/google-cloud-ruby,quartzmo/google-cloud-ruby,googleapis/google-cloud-ruby,quartzmo/google-cloud-ruby,swcloud/google-cloud-ruby,CloudVLab/google-cloud-ruby,quartzmo/google-cloud-ruby,dazuma/google-cloud-ruby,landrito/google-cloud-ruby,quartzmo/google-cloud-ruby,swcloud/google-cloud-ruby,CloudVLab/google-cloud-ruby,yancya/gcloud-ruby,CloudVLab/google-cloud-ruby