Bump EPEL release rpm for RHEL 7 to 7.0-2

Change-Id: I67aca97770cd6f89072e881ae37e39d70bfaba53
retry apt operations to avoid network issues

One of the major gate failures is do to something being wrong with
the apt mirrors. The Acquire group provides an implicit retry on
network operations which seems like it might be helpful here.

Ref: http://linux.die.net/man/5/apt.conf

Change-Id: I099f47ed86ad6a3d4296bff4cce75e7f7d946d27
Related-Bug: #1286635
Handle failure of openstack endpoint

Change 4f7bf6963a1e9ae03bc0ae9189874cba561ad62f introduced finding the
endpoint via "openstack endpoint show" only.  Previously that output
was piped through grep, etc. so it handled fell back to a blank
output when the endpoints were not available.

Ignore failures of this command so the blank output is matched

Change-Id: Iae2f09784ffa38efd2f858513bf284c84c32edac
Add an environment variable to enable extensions in keystone

Following https://review.openstack.org/#/c/44401/3

Change-Id: I8e0391cd68e29e6d57c0f35517bf4155110861c7
Closes-Bug: #1218733
Co-Authored-By: Yong Sheng Gong <gongysh@unitedstack.com>
Merge "retry apt operations to avoid network issues"
Merge "Use curl to download from github.com"
Merge "Handle failure of openstack endpoint"
Merge "Add an environment variable to enable extensions in keystone"
Merge "XenAPI: Tail output from stack.sh"
Merge "Bump EPEL release rpm for RHEL 7 to 7.0-2"
Merge commit 'refs/changes/83/86083/2' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch