Support adding extra sys_path

autoload/jedi.vim

@@ -36,6 +36,7 @@ let s:default_settings = {
     \ 'quickfix_window_height': 10,
     \ 'force_py_version': "'auto'",
     \ 'environment_path': "'auto'",
+    \ 'added_sys_path': "'[]'",
     \ 'project_path': "'auto'",
     \ 'smart_auto_mappings': 0,
     \ 'use_tag_stack': 1