tempest: fix virtenv installation

The install_venv.sh script has set -e and -u but sourcing
venv/bin/activate results in the error below
  line 8: _OLD_VIRTUAL_PATH: unbound variable
The fix turns off -u temporarily to source the 'activate' file
Merge pull request #17 from sthaha/fix/virtenv-installation

tempest: fix virtenv installation
Foreman playbook now uses foreman_nodes as a variable passed to get_nodes
Add tags to foreman playbook
Add support for using a specific RDO repo
Fedora: sudo and workarounds for cloud image
Fedora 19: added required work arounds for the fedora 19 cloud image to work
AIO_NEUTRON: add user root to nodes, facts
Reboot handler: sudo off