Change the listening port from 9000 to 80 (#685)
Change the listening port from 9000 to 80 (#685)

This makes our Quickstarts consistent such that port 80 is used in both
examples on GCE and GKE.
JavaRabbit/CS496_capstone,hashems/Mobile-Cloud-Development-Projects,hashems/Mobile-Cloud-Development-Projects,canglade/NLP,sharbison3/python-docs-samples,GoogleCloudPlatform/python-docs-samples,sharbison3/python-docs-samples,hashems/Mobile-Cloud-Development-Projects,JavaRabbit/CS496_capstone,BrandonY/python-docs-samples,GoogleCloudPlatform/python-docs-samples,sharbison3/python-docs-samples,sharbison3/python-docs-samples,hashems/Mobile-Cloud-Development-Projects,canglade/NLP,JavaRabbit/CS496_capstone,BrandonY/python-docs-samples,JavaRabbit/CS496_capstone,GoogleCloudPlatform/python-docs-samples,BrandonY/python-docs-samples,canglade/NLP,canglade/NLP,BrandonY/python-docs-samples,GoogleCloudPlatform/python-docs-samples