Add total RAM, CPUs and disk size to servers summary as well as disk usage in percent. Fixes https://github.com/GNS3/gns3-server/issues/1532

tests/handlers/api/controller/test_compute.py

@@ -133,9 +133,13 @@ async def test_compute_list(controller_api):
                 'name': 'My super server',
                 'cpu_usage_percent': None,
                 'memory_usage_percent': None,
+                'disk_usage_percent': None,
                 'last_error': None,
                 'capabilities': {
                     'version': None,
+                    'cpus': None,
+                    'memory': None,
+                    'disk_size': None,
                     'node_types': []
                 }
             }