Align required args for 'fuel2 graph upload'

Dissallow 'fuel2 graph uplod' command execution without
required args (-e ENV | -r RELEASE | -p PLUGIN), e.g.:
  usage: fuel2 graph upload [-h]
         (-e ENV | -r RELEASE | -p PLUGIN) [-t TYPE] -f FILE

Change-Id: I4fb1215874a849ea032afadb9604fca0dc0784a1
Closes-Bug: 1587837

fuelclient/commands/graph.py

@@ -59,7 +59,7 @@ class GraphUpload(base.BaseCommand, FileMethodsMixin):
 
     def get_parser(self, prog_name):
         parser = super(GraphUpload, self).get_parser(prog_name)
-        graph_class = parser.add_mutually_exclusive_group()
+        graph_class = parser.add_mutually_exclusive_group(required=True)
 
         graph_class.add_argument('-e',
                                  '--env',

fuelclient/tests/unit/v2/cli/test_deployment_graph.py

@@ -77,6 +77,13 @@ class TestGraphActions(test_engine.BaseCLITest):
             )
         )
 
+    @mock.patch('sys.stderr')
+    def test_upload_fail(self, mocked_stderr):
+        cmd = 'graph upload --file new_graph.yaml'
+        self.assertRaises(SystemExit, self.exec_command, cmd)
+        self.assertIn('-e/--env -r/--release -p/--plugin',
+                      mocked_stderr.write.call_args_list[-1][0][0])
+
     def test_execute(self):
         self._test_cmd(
             'execute',