Make code more clear following code review.

theano/sparse/__init__.py

@@ -4,7 +4,7 @@ import theano.scipy
 enable_sparse = False
 if theano.scipy.scipy_available:
     import scipy
-    if not scipy.__version__ < '0.7':
+    if scipy.__version__ >= '0.7':
         enable_sparse = True
     else:
         sys.stderr.write("WARNING: scipy version = %s. We request version >=0.7.0 for the sparse code as it has bugs fixed in the sparse matrix code.\n" % scipy.__version__)