Fix invalid forwarder list due to not using Unicode text.

When using ipadnsfowardzone with a target host that uses Python 2,
it fails to add new zones due to unicode and str being different on
that version. This patch fixes this behavior ensuring the module
works on both Python verisons 2.7 and 3.x.

plugins/modules/ipadnsforwardzone.py

@@ -106,6 +106,7 @@ RETURN = '''
 
 
 from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils._text import to_text
 from ansible.module_utils.ansible_freeipa_module import temp_kinit, \
     temp_kdestroy, valid_creds, api_connect, api_command, compare_args_ipa, \
     module_params_get
@@ -150,7 +151,7 @@ def forwarder_list(forwarders):
             formatter = "{ip_address} port {port}"
         else:
             formatter = "{ip_address}"
-        fwd_list.append(formatter.format(**forwarder))
+        fwd_list.append(to_text(formatter.format(**forwarder)))
     return fwd_list