Allow PATCHing users

This is used to set the username from the settings view.

pillarsdk/users.py

@@ -4,11 +4,12 @@ from .resource import List
 from .resource import Find
 from .resource import Create
 from .resource import Post
+from .resource import Patch
 from .resource import Update
 from .resource import Delete
 
 
-class User(List, Find, Create, Post, Update, Delete):
+class User(List, Find, Create, Post, Update, Delete, Patch):
     """User class wrapping the REST nodes endpoint
     """
     path = "users"
@@ -30,3 +31,10 @@ class User(List, Find, Create, Post, Update, Delete):
         """Returns info about the current user, identified by auth token."""
 
         return cls.find_from_endpoint('/users/me', params=params, api=api)
+
+    def set_username(self, new_username: str, api):
+        """PATCH the user to set the new username."""
+
+        self.username = new_username
+        return self.patch({'op': 'set-username', 'username': new_username},
+                          api=api)