Move django import and initialization inside the offline client class

This allows to import the class without triggering the import and
initialization of django and instead deferring it to when (and if) the
class is instanciated.

Change-Id: I79be90eb877f21b5254f116e51cc78b310c8674c

ara/clients/offline.py

@@ -22,26 +22,27 @@ import json
 import logging
 import os
 
-try:
-    from django import setup as django_setup
-    from django.core.management import execute_from_command_line
-    from django.test import Client
-
-    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'ara.server.settings')
-
-    # Automatically create the database and run migrations (is there a better way?)
-    execute_from_command_line(['django', 'migrate'])
-
-    # Set up the things Django needs
-    django_setup()
-except ImportError as e:
-    print('ERROR: The offline client requires ara-server to be installed')
-    raise e
-
 
 class AraOfflineClient(object):
     def __init__(self):
         self.log = logging.getLogger(__name__)
+
+        try:
+            from django import setup as django_setup
+            from django.core.management import execute_from_command_line
+            from django.test import Client
+
+            os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'ara.server.settings')
+
+            # Automatically create the database and run migrations (is there a better way?)
+            execute_from_command_line(['django', 'migrate'])
+
+            # Set up the things Django needs
+            django_setup()
+        except ImportError as e:
+            self.log.error('The offline client requires ara-server to be installed')
+            raise e
+
         self.client = Client()
 
     def _request(self, method, endpoint, **kwargs):