[chore] Remove redundant imports

This also removes the historical patch for NullHandler implemented in bbf1c54, as it has been available since Python 3.1.

discord/__init__.py

@@ -64,11 +64,4 @@ VersionInfo = namedtuple('VersionInfo', 'major minor micro releaselevel serial')
 
 version_info = VersionInfo(major=1, minor=6, micro=0, releaselevel='alpha', serial=0)
 
-try:
-    from logging import NullHandler
-except ImportError:
-    class NullHandler(logging.Handler):
-        def emit(self, record):
-            pass
-
-logging.getLogger(__name__).addHandler(NullHandler())
+logging.getLogger(__name__).addHandler(logging.NullHandler())