install test-reqs when TESTONLY packages are installed

INSTALL_TESTONLY_PACKAGES in devstack only impacts .deb/.rpm files
even though most of our test requirements are actually specified
in python. This will do an explicit install of test-requirements.txt
if pip_install is called with args that look like a directory,
and test-requirements.txt exists in that directory.

Change-Id: Id21e282ddc945c819c9c8c4d724658e28bfde785
Move to epel 7-1 release

EPEL7 has updated.  AFAIK there is no better way to determine this; we
could possibly scrape [1] but this just seems to replace one problem
with another (maintaining the scraping)

[1] http://download.fedoraproject.org/pub/epel/7/x86_64/repoview/epel-release.html

Change-Id: Iadf66c92fcf31edeb0f364a5b1de5d87630e9a42
Merge "Move to epel 7-1 release"
Merge "install test-reqs when TESTONLY packages are installed"
Merge branch 'master' of https://github.com/openstack-dev/devstack