Add in delete:entry command

Adds in the delete:entry command by using the channel_entries api. Super admin status must be set and also the can_delete_all_entries must be set to yes as well
````
        ee()->session->userdata['group_id'] = '1';
        ee()->session->userdata['can_delete_all_entries'] = 'y';
````

The next step to this which I'll add in later is the ability to pass in multiple entries to delete.