Capomastro uses transaction.commit_unless_managed which is a no-op and will be removed in django 1.8

When running tox tests for capomastro on django 1.7 I get:

Creating test database for alias 'default'...
.../capomastro/credentials/management/commands/import_sshkeypair.py:29: RemovedInDjango18Warning: 'commit_unless_managed' is now a no-op.
  transaction.commit_unless_managed()

the tests pass, but when I let the requirements.txt file install the latest matching django version (1.8a1 at the moment), the removal has taken effect and I get a test failure:

======================================================================
ERROR: test_run_command_with_key_import (credentials.management.commands.tests.test_import_sshkeypair.ImportSshKeytTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/capomastro/credentials/management/commands/tests/test_import_sshkeypair.py", line 39, in test_run_command_with_key_import
    update=False)
  File "/capomastro/.tox/py27/local/lib/python2.7/site-packages/django/core/management/base.py", line 441, in execute
    output = self.handle(*args, **options)
  File "/capomastro/credentials/management/commands/import_sshkeypair.py", line 29, in handle
    transaction.commit_unless_managed()
AttributeError: 'module' object has no attribute 'commit_unless_managed'

Removing the call to transaction.commit_unless_managed() from credentials/management/commands/import_sshkeypair.py seems to fix this issue.