<!--- 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 -->

response = self.get_request(self.root_uri + storage_uri)
            if response['ret'] is False:
                return response
            result['ret'] = True
            data = response['data']
            if data.get('Members'):
                for controller in data[u'Members']:
                    controller_list.append(controller[u'@odata.id'])
                for c in controller_list:
                    uri = self.root_uri + c
                    response = self.get_request(uri)
                    if response['ret'] is False:
                        return response
                    data = response['data']
                    controller_name = 'Controller 1'
                    if 'StorageControllers' in data:
                        sc = data['StorageControllers']
                        if sc:
                            if 'Name' in sc[0]:
                                controller_name = sc[0]['Name']
                            else:
                                sc_id = sc[0].get('Id', '1')
                                controller_name = 'Controller %s' % sc_id
                    volume_results = []
                    if 'Volumes' in data:
                        
                        volumes_uri = data[u'Volumes'][u'@odata.id']
                        response = self.get_request(self.root_uri + volumes_uri)
                        data = response['data']
                        if data.get('Members'):