Add support for Plex JWT Authentication (#1554)

* Add private.key and public.key to .gitignore

* Add `MyPlexJWTAuth` class

* Add `utils.plexJWTAuth` helper function

* Update optional dependencies for Plex JWT authentication

* Add method to retrieve Plex JWT without initial Plex token

* Update doc strings

* Switch MyPlexJWTLogin to JSON response

* Remove cached data properties

* Guard against None keypair

* Use UTC timezone for jwt

Author: JonnyWong16

.gitignore

@@ -27,6 +27,8 @@ pyvenv.cfg
 MANIFEST
 venv/
 .venv/
+private.key
+public.key
 
 # path for the test lib.
 plex/

README.rst

@@ -37,6 +37,7 @@ Installation & Documentation
 .. code-block:: python
 
     pip install plexapi[alert]  # Install with dependencies required for plexapi.alert
+    pip install plexapi[jwt]    # Install with dependencies required for Plex JWT authentication
 
 Documentation_ can be found at Read the Docs.