Make Homebrew-related modules run on Python 3

Both the `homebrew` and `homebrew_cask` modules iterate over
dictionaries using `iteritems`. This is a Python 2-specific method whose
behavior is similar to `items` in Python 3+. The `iteritems` function in
the six library was designed to make it possible to use the correct
method.

lib/ansible/modules/extras/packaging/os/homebrew.py

@@ -101,6 +101,8 @@ EXAMPLES = '''
 import os.path
 import re
 
+from ansible.module_utils.six import iteritems
+
 
 # exceptions -------------------------------------------------------------- {{{
 class HomebrewException(Exception):
@@ -348,7 +350,7 @@ class Homebrew(object):
         self.message = ''
 
     def _setup_instance_vars(self, **kwargs):
-        for key, val in kwargs.iteritems():
+        for key, val in iteritems(kwargs):
             setattr(self, key, val)
 
     def _prep(self):

lib/ansible/modules/extras/packaging/os/homebrew_cask.py

@@ -75,6 +75,8 @@ EXAMPLES = '''
 import os.path
 import re
 
+from ansible.module_utils.six import iteritems
+
 
 # exceptions -------------------------------------------------------------- {{{
 class HomebrewCaskException(Exception):
@@ -309,7 +311,7 @@ class HomebrewCask(object):
         self.message = ''
 
     def _setup_instance_vars(self, **kwargs):
-        for key, val in kwargs.iteritems():
+        for key, val in iteritems(kwargs):
             setattr(self, key, val)
 
     def _prep(self):