Pin google-gax to public repo
Pin google-gax to public repo

This is to work around a dependency on an unreleased change that made its way
into master. Remove this when google-gax 0.8.1 is released.

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