Add multi-store support

Added multi-store support. User can now use '--backend'
option to pass desired store while creating, uploading or
importing image to speific store backend.

Added new command 'stores-info' which will return available
stores information to the user.

Related to blueprint multi-store
Change-Id: I7370094fc4ed47205b5a86a18b22aaa7b9457e5b

glanceclient/tests/unit/v2/test_shell_v2.py

@@ -95,6 +95,7 @@ class ShellV2Test(testtools.TestCase):
         # dict directly, it throws an AttributeError.
         class Args(object):
             def __init__(self, entries):
+                self.backend = None
                 self.__dict__.update(entries)
 
         return Args(args)
@@ -1102,7 +1103,8 @@ class ShellV2Test(testtools.TestCase):
             utils.get_data_file = mock.Mock(return_value='testfile')
             mocked_upload.return_value = None
             test_shell.do_image_upload(self.gc, args)
-            mocked_upload.assert_called_once_with('IMG-01', 'testfile', 1024)
+            mocked_upload.assert_called_once_with('IMG-01', 'testfile', 1024,
+                                                  backend=None)
 
     @mock.patch('glanceclient.common.utils.exit')
     def test_neg_image_import_not_available(self, mock_utils_exit):
@@ -1263,7 +1265,7 @@ class ShellV2Test(testtools.TestCase):
                     mock_import.return_value = None
                     test_shell.do_image_import(self.gc, args)
                     mock_import.assert_called_once_with(
-                        'IMG-01', 'glance-direct', None)
+                        'IMG-01', 'glance-direct', None, backend=None)
 
     def test_image_import_web_download(self):
         args = self._make_args(
@@ -1281,7 +1283,7 @@ class ShellV2Test(testtools.TestCase):
                     test_shell.do_image_import(self.gc, args)
                     mock_import.assert_called_once_with(
                         'IMG-01', 'web-download',
-                        'http://example.com/image.qcow')
+                        'http://example.com/image.qcow', backend=None)
 
     @mock.patch('glanceclient.common.utils.print_image')
     def test_image_import_no_print_image(self, mocked_utils_print_image):
@@ -1299,7 +1301,7 @@ class ShellV2Test(testtools.TestCase):
                     mock_import.return_value = None
                     test_shell.do_image_import(self.gc, args)
                     mock_import.assert_called_once_with(
-                        'IMG-02', 'glance-direct', None)
+                        'IMG-02', 'glance-direct', None, backend=None)
                     mocked_utils_print_image.assert_not_called()
 
     def test_image_download(self):