<!--- Verify first that your feature was not already discussed on GitHub -->
<!--- Complete *all* sections as described, this form is processed automatically -->

##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
This feature would implement a ClearSessions command for the Sessions category of redfish_command, to clear all active sessions.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
redfish_command.py
redfish_utils.py

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->
This command would help user to clear all active sessions.

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- HINT: You can also paste gist.github.com links for larger files -->

headers = PATCH_HEADERS
        r = self.get_request(uri)
        if r['ret']:
            
            etag = r['headers'].get('etag')
            if not etag:
                etag = r['data'].get('@odata.etag')
            if etag:
                
                headers = dict(headers)
                headers['If-Match'] = etag
        try:
            resp = open_url(uri, data=json.dumps(pyld),
                            headers=headers, method="PATCH",
                            url_username=self.creds['user'],
                            url_password=self.creds['pswd'],
                            force_basic_auth=True, validate_certs=False,
                            follow_redirects='all',
                            use_proxy=True, timeout=self.timeout)
        except HTTPError as e:
            msg = self._get_extended_message(e)
            return {'ret': False,
                    'msg': "HTTP Error %s on PATCH request to '%s', extended message: '%s'"
                           % (e.code, uri, msg),
                    'status': e.code}
        except URLError as e:
            return {'ret': False, 'msg': "URL Error on PATCH request to '%s': '%s'"
                                         % (uri, e.reason)}