need horizon user and group to deploy openstack-horizon

[hawkwang]

See following statements:

• name: Setup horizon var dir
  file: dest=/var/lib/openstack-dashboard owner=horizon group=horizon mode=755 state=directory
  notify:
• Restart apache2

We need modify as follows:
1）roles/openstack-horizon/vars/main.yml
add
horizon_group: horizon
horizon_user: horizon

2）roles/openstack-horizon/tasks/main.yml
add

• name: Setup group
  group: name={{horizon_group}} system=yes
• name: Setup user
  user: name={{horizon_user}} system=yes group={{horizon_group}}

[craigbr]

Those look like good changes. Can you fork the repository, make the changes and do a pull request? We will review and merge them. Thanks for helping to improve monasca