Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/oauthlib/oauth2/rfc6749/endpoints/__init__.py

@@ -0,0 +1,17 @@
+"""
+oauthlib.oauth2.rfc6749
+~~~~~~~~~~~~~~~~~~~~~~~
+
+This module is an implementation of various logic needed
+for consuming and providing OAuth 2.0 RFC6749.
+"""
+from .authorization import AuthorizationEndpoint
+from .introspect import IntrospectEndpoint
+from .metadata import MetadataEndpoint
+from .pre_configured import (
+    BackendApplicationServer, LegacyApplicationServer, MobileApplicationServer,
+    Server, WebApplicationServer,
+)
+from .resource import ResourceEndpoint
+from .revocation import RevocationEndpoint
+from .token import TokenEndpoint