<!--- 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 -->

def __init__(self, creds, root_uri, timeout, module, resource_id=None,
                 data_modification=False):
        self.root_uri = root_uri
        self.creds = creds
        self.timeout = timeout
        self.module = module
        self.service_root = '/redfish/v1/'
        self.resource_id = resource_id
        self.data_modification = data_modification
        self._init_session()
    
    def get_request(self, uri):