[RFE] Allow multiple groups creation.

Adding an option `groups` to create multiple groups in one operation.
Adding tests (present/absent/external/nonposix) with server and
client context.
Simple example of `groups` option:
```
tasks:
- name: Ensure 2 groups are present
  ipagroup:
    ipaadmin_password: SomeADMINpassword
    groups:
    - name: group1
    - name: group2
```

Signed-off-by: Denis Karpelevich <dkarpele@redhat.com>

playbooks/group/add-groups.yml

@@ -0,0 +1,32 @@
+---
+- name: Playbook to handle multiple groups
+  hosts: ipaserver
+
+  tasks:
+  - name: Create multiple groups ops, sysops
+    ipagroup:
+      ipaadmin_password: SomeADMINpassword
+      groups:
+      - name: ops
+        gidnumber: 1234
+      - name: sysops
+
+  - name: Add user and group members to groups sysops and appops
+    ipagroup:
+      ipaadmin_password: SomeADMINpassword
+      groups:
+      - name: sysops
+        user:
+          - user1
+      - name: appops
+        group:
+          - group2
+
+  - name: Create multiple non-POSIX and external groups
+    ipagroup:
+      ipaadmin_password: SomeADMINpassword
+      groups:
+      - name: nongroup
+        nonposix: true
+      - name: extgroup
+        external: true