<!--- 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 + self.manager_uri)
        if response['ret'] is False:
            return response
        data = response['data']
        if 'LogServices' not in data:
            return {'ret': False, 'msg': "LogServices resource not found"}
        
        logs_uri = data["LogServices"]["@odata.id"]
        response = self.get_request(self.root_uri + logs_uri)
        if response['ret'] is False:
            return response
        data = response['data']
        for log_svcs_entry in data[u'Members']:
            response = self.get_request(self.root_uri + log_svcs_entry["@odata.id"])
            if response['ret'] is False:
                return response
            _data = response['data']
            
            if "Actions" in _data:
                if "#LogService.ClearLog" in _data[u"Actions"]:
                    self.post_request(self.root_uri + _data[u"Actions"]["#LogService.ClearLog"]["target"], {})
                    if response['ret'] is False:
                        return response
        return {'ret': True}
    def aggregate(self, func, uri_list, uri_name):