remove: dead workaround for CPython bug #10923 (fixed in 3.3)

The workaround pre-loaded the UTF-8 encoding module to avoid a deadlock
when importing from multiple threads.  This bug was fixed in Python 3.3.

Author: mykaul

cassandra/cluster.py

@@ -179,12 +179,6 @@ def _connection_reduce_fn(val,import_fn):
     raise DependencyException("Exception loading connection class dependencies", excs)
 DefaultConnection = conn_class
 
-# Forces load of utf8 encoding module to avoid deadlock that occurs
-# if code that is being imported tries to import the module in a seperate
-# thread.
-# See http://bugs.python.org/issue10923
-"".encode('utf8')
-
 log = logging.getLogger(__name__)