fix setup.sh URL and bash interpretation

* s|/master/openstack-installer|/openstack-installer/master|

* use <() instead of -c "$()" to avoid potential buffer limits or
  escaping issues.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #129 from dachary/wip-setup-sh

fix setup.sh URL and bash interpretation