Use freezerclient.client to support v1 or v2

The python-freezerclient 2.0.0 is released now. We can directly use
freezerclinent.client to support api v1 or v2.

Change-Id: I30ad8694d137e0fab081b0f8ded842caa723c86f

disaster_recovery/api/api.py

@@ -17,13 +17,7 @@ from oslo_log import log
 
 from django.conf import settings
 from horizon.utils.memoized import memoized  # noqa
-
-# When  python-freezerclient 2.0 released, directly use freezerclient.client
-# as freezer_client.
-# The current python-freezerclient version hasn't freezerclient.client module.
-# from freezerclient import client as freezer_client
-
-from freezerclient.v2 import client as freezer_client
+from freezerclient import client as freezer_client
 
 from disaster_recovery import utils
 

lower-constraints.txt

@@ -39,7 +39,7 @@ Pygments==2.2.0
 pylint==1.4.5
 pyparsing==2.2.0
 pyperclip==1.6.0
-python-freezerclient==1.3.0
+python-freezerclient==2.0.0
 python-mimeparse==1.6.0
 python-subunit==1.2.0
 pytz==2018.3

requirements.txt

@@ -1,7 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-python-freezerclient>=1.3.0 # Apache-2.0
+python-freezerclient>=2.0.0 # Apache-2.0
 oslo.log>=3.36.0  # Apache-2.0
 
 # OpenStack CI will install the following projects from git