use devpi on aws as the local pypi, and remove http_proxy

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 On branch cnnet
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	modified:   roles/common/defaults/main.yml
	modified:   roles/common/tasks/main.yml
	modified:   roles/discern/defaults/main.yml
	modified:   roles/discern/tasks/deploy.yml
	modified:   roles/edx_ansible/defaults/main.yml
	modified:   roles/edx_ansible/tasks/deploy.yml
	modified:   roles/edxapp/defaults/main.yml
	modified:   roles/ora/defaults/main.yml
	modified:   roles/ora/tasks/deploy.yml
	modified:   roles/ora/tasks/ease.yml
	modified:   roles/supervisor/defaults/main.yml
	modified:   roles/xqueue/defaults/main.yml
	modified:   roles/xqueue/tasks/deploy.yml