Refactored Watcher codebase to add py34 support

Even though Watcher was mentioning python 3.4 as supported, it
really wasn't the case as all the unit tests were not passing in this
version of Python.

This patchset fixes all the failing tests in Python 3.4 while
keeping Watcher Python 2.7 compatible.

DocImpact
BugImpact
Change-Id: Ie74acc08ef0a2899349a4b419728c89e416a18cb

watcher/common/exception.py

@@ -44,7 +44,7 @@ CONF.register_opts(exc_log_opts)
 
 def _cleanse_dict(original):
     """Strip all admin_password, new_pass, rescue_pass keys from a dict."""
-    return dict((k, v) for k, v in original.iteritems() if "_pass" not in k)
+    return dict((k, v) for k, v in six.iteritems(original) if "_pass" not in k)
 
 
 class WatcherException(Exception):
@@ -77,7 +77,7 @@ class WatcherException(Exception):
                 # kwargs doesn't match a variable in the message
                 # log the issue and the kwargs
                 LOG.exception(_LE('Exception in string format operation'))
-                for name, value in kwargs.iteritems():
+                for name, value in six.iteritems(kwargs):
                     LOG.error("%s: %s" % (name, value))
 
                 if CONF.fatal_exception_format_errors:
@@ -231,7 +231,7 @@ class PatchError(Invalid):
 class BaseException(Exception):
 
     def __init__(self, desc=""):
-        if (not isinstance(desc, basestring)):
+        if (not isinstance(desc, six.string_types)):
             raise IllegalArgumentException(
                 "Description must be an instance of str")