Remove old module redirection.

theano/sandbox/gpuarray/__init__.py

-"""Placeholder for new gpuarray backend in sandbox. Supports old pickles
-which refered to theano.sandbox.gpuarray."""
-
-import warnings
-from theano.gpuarray import *
-
-message = ("theano.sandbox.gpuarray has been moved to theano.gpuarray. "
-    "Please update your code and pickles. If the warning persists, "
-    "clear theano's cache ('$theano/bin/theano-cache clear').")
-warnings.warn(message)