cli: add delete http method

Add delete function to OgRest class. Enable ogCLI to send HTTP
requests using DELETE as request verb.

Encapsulates requests python module .delete() method.

cli/cli.py

@@ -48,6 +48,19 @@ class OgREST():
             sys.exit(f"Cannot connect to ogServer: {e}")
         return r
 
+    def delete(self, path, payload):
+        try:
+            r = requests.delete(f'{self.URL}{path}',
+                                headers=self.HEADERS,
+                                json=payload)
+            print(r.text)
+            if r.status_code != 200:
+                sys.exit(f"Unsuccessful request to ogServer: "
+                         f"{r.status_code} HTTP status code")
+        except IOError as e:
+            sys.exit(f"Cannot connect to ogServer: {e}")
+        return r
+
 
 class OgCLI():
     def __init__(self, cfg):