1) Description of problem

The current ceph-iscsi installer playbooks for RHCS2.x enforces the RHEL version to be 7.3.

Since 7.4 has been released, this makes it impossible to install iSCSI on a RHEL7.4 node. 

In `roles/ceph-iscsi-gw/tasks/main.yml` from the package `ceph-iscsi-ansible.noarch` version `1.5-5.el7scon`:

~~~
- name: OS Compatibility Check (RHEL 7.3)
  assert:
    that:
      - "ansible_distribution == 'RedHat'"
      - "ansible_distribution_version == '7.3'"
~~~

2) Version-Release number of selected component (if applicable):

RHCS2.3
RHEL7.4
ceph-iscsi-ansible-1.5-5.el7scon.noarch.rpm

3) How reproducible:

Always

4) Steps to Reproduce:

* Use a RHEL7.4 node
* Run the iscsi playbooks with `ansible-playbook ceph-iscsi-gw.yml`
* The installation process will error out with:

~~~
PLAY [ceph-iscsi-gw] ***********************************************************

TASK [setup] *******************************************************************
ok: [target2]
ok: [target1]

TASK [ceph-iscsi-gw : OS Compatibility Check (RHEL 7.3)] ***********************
fatal: [target1]: FAILED! => {
    "assertion": "ansible_distribution_version == '7.3'", 
    "changed": false, 
    "evaluated_to": false, 
    "failed": true
}
fatal: [target2]: FAILED! => {
    "assertion": "ansible_distribution_version == '7.3'", 
    "changed": false, 
    "evaluated_to": false, 
    "failed": true
}
	to retry, use: --limit @/usr/share/ceph-ansible/ceph-iscsi-gw.retry

PLAY RECAP *********************************************************************
target1                    : ok=1    changed=0    unreachable=0    failed=1   
target2                    : ok=1    changed=0    unreachable=0    failed=1  
~~~

5) Additional info:

Changing the directive "ansible_distribution_version == '7.3'" to "ansible_distribution_version >= '7.3'"  in `/usr/share/ceph-ansible/roles/ceph-iscsi-gw/tasks/main.yml` fixes the problem, since it evaluates if the installation is above 7.3.