Reorder imp and importlib imports

Python 3.4 deprecated the imp module in favor of importlib. Because we
use imp module by default, using selinux package with Python 3.4+
emits a deprecation warning:

   DeprecationWarning: the imp module is deprecated in favour of
   importlib; see the module's documentation for alternative uses.

This commit makes the importlib default module and imp a fallback one.

Author: Tadej Borovšak

selinux/__init__.py

@@ -16,9 +16,9 @@
 import sys
 
 try:
-    from imp import reload  # type: ignore  # noqa
-except ImportError:  # py34+
     from importlib import reload  # type: ignore  # noqa
+except ImportError:  # py < 34
+    from imp import reload  # type: ignore  # noqa
 
 
 class add_path(object):