Fix undefined basestring and unicode in py35

In py3 basestring and unicode are no longer valid,
and should use `str` instead. In order to cover
py2 and py3, we change to use six lib to cover both.
Closes-Bug: #1682015

Change-Id: I3159470965e3a20161ff0e997af625b45ebe21fa

hot/software-config/elements/heat-config-docker-cmd/install.d/hook-docker-cmd.py

@@ -15,6 +15,7 @@
 import json
 import logging
 import os
+import six
 import subprocess
 import sys
 import yaml
@@ -99,7 +100,7 @@ def main(argv=sys.argv):
             if key in ['environment', 'volumes', 'volumes_from']:
                 for value in config[container][key]:
                     # Somehow the lists get empty values sometimes
-                    if type(value) is unicode and not value.strip():
+                    if type(value) is six.text_type and not value.strip():
                         continue
                     cmd.append(docker_arg_map(key, value))
             elif key == 'image':

hot/software-config/elements/heat-config-docker-compose/install.d/hook-docker-compose.py

@@ -17,6 +17,7 @@ import dpath
 import json
 import logging
 import os
+import six
 import subprocess
 import sys
 import yaml
@@ -87,7 +88,7 @@ def main(argv=sys.argv):
     for value in dpath.util.values(config, '*/env_file'):
         if isinstance(value, list):
             compose_env_files.extend(value)
-        elif isinstance(value, basestring):
+        elif isinstance(value, six.string_types):
             compose_env_files.extend([value])
 
     input_env_files = {}

hot/software-config/elements/heat-config/os-refresh-config/configure.d/55-heat-config

@@ -21,6 +21,7 @@ import subprocess
 import sys
 
 import requests
+import six
 
 HOOKS_DIR_PATHS = (
     os.environ.get('HEAT_CONFIG_HOOKS'),
@@ -93,7 +94,7 @@ def invoke_hook(c, log):
     hot_inputs = c.get('inputs', [])
     for hot_input in hot_inputs:
         if hot_input.get('type', None) == 'String' and \
-                not isinstance(hot_input['value'], basestring):
+                not isinstance(hot_input['value'], six.text_type):
             hot_input['value'] = str(hot_input['value'])
     iv = dict((i['name'], i['value']) for i in c['inputs'])
     # The group property indicates whether it is softwarecomponent or