ipasudorule: Allow setting groups for runasuser.

On IPA CLI sudorule-add/del-runasuser accept 'group' as a parameter,
and this option was missing in ansible-freeipa ipasudorule module.

This patch adds a new parameter 'runasuser_group' to allow setting
Groups of RunAs Users, as allowed by CLI and WebUI.

New example playboks can be found at:

    playbooks/sudorule/ensure-sudorule-runasusesr-group-is-absent.yml
    playbooks/sudorule/ensure-sudorule-runasusesr-group-is-present.yml

README-sudorule.md

@@ -93,6 +93,26 @@ Example playbook to make sure sudocmds are not present in Sudo Rule:
       state: absent
 ```
 
+
+Example playbook to ensure a Group of RunAs User is present in sudo rule:
+
+```yaml
+---
+- name: Playbook to manage sudorule member
+  hosts: ipaserver
+  become: no
+  gather_facts: no
+
+  tasks:
+  - name: Ensure sudorule 'runasuser' has 'ipasuers' group as runas users.
+    ipasudorule:
+      ipaadmin_password: SomeADMINpassword
+      name: testrule1
+      runasuser_group: ipausers
+      action: member
+```
+
+
 Example playbook to make sure Sudo Rule is absent:
 
 ```yaml