Rename pycompat to pycompat24

This change makes it so we know when it is safe to get rid of the module
(when we stop supporting python2.4) and makes it easier for us to find
code that is using the functions in there to update.

If needed, we'll create a pycompat26 and pycompat27 as well.  These
files are for functions that are needed on that python version to write
portable code.  So python-2.4 compatible modules may need code in
pycompat24, python26+ modules may need code in pycompat26, etc.  If
a function is needed in multiple python versions, we should implement it
in an internal common file and use import to put it in the namespace for
each pycompatXY module.

lib/ansible/module_utils/basic.py

@@ -220,7 +220,7 @@ except ImportError:
 _literal_eval = literal_eval
 
 # Backwards compat.  There were present in basic.py before
-from ansible.module_utils.pycompat import get_exception
+from ansible.module_utils.pycompat24 import get_exception
 
 # Internal global holding passed in params and constants.  This is consulted
 # in case multiple AnsibleModules are created.  Otherwise each AnsibleModule