Performance improvement using in-operator for hash lookups

Just a small cleanup for the existing occurrences.

Using the in-operator for hash lookups is faster than using .has_key()
http://stackoverflow.com/questions/1323410/has-key-or-in

lib/ansible/modules/packaging/os/rhn_register.py

@@ -163,7 +163,7 @@ class Rhn(RegistrationBase):
         def get_option_default(self, key, default=''):
             # ignore pep8 W601 errors for this line
             # setting this to use 'in' does not work in the rhn library
-            if self.has_key(key):
+            if key in self:
                 return self[key]
             else:
                 return default

lib/ansible/modules/system/user.py

@@ -1715,7 +1715,7 @@ class DarwinUser(User):
                 self.chown_homedir(int(self.uid), int(self.group), self.home)
 
         for field in self.fields:
-            if self.__dict__.has_key(field[0]) and self.__dict__[field[0]]:
+            if field[0] in self.__dict__ and self.__dict__[field[0]]:
 
                 cmd = self._get_dscl()
                 cmd += [ '-create', '/Users/%s' % self.name, field[1], self.__dict__[field[0]]]
@@ -1752,7 +1752,7 @@ class DarwinUser(User):
             self._make_group_numerical()
 
         for field in self.fields:
-            if self.__dict__.has_key(field[0]) and self.__dict__[field[0]]:
+            if field[0] in self.__dict__ and self.__dict__[field[0]]:
                 current = self._get_user_property(field[1])
                 if current is None or current != self.__dict__[field[0]]:
                     cmd = self._get_dscl()