Move 2.7 to 2 (#635)

Closes #579.

stdlib/2/grp.pyi

@@ -0,0 +1,11 @@
+from typing import Optional, List
+
+class struct_group(object):
+    gr_name = ...  # type: Optional[str]
+    gr_passwd = ...  # type: Optional[str]
+    gr_gid = ...  # type: int
+    gr_mem = ...  # type: List[str]
+
+def getgrall() -> List[struct_group]: ...
+def getgrgid(id: int) -> struct_group: ...
+def getgrnam(name: str) -> struct_group: ...