'Runs OfflineImap
:returns: (rescode, stdout (as unicode))'

@classmethod
def run_OLI(cls):

    try:
        output = subprocess.check_output([cls.cmd, ('-c%s' % os.path.join(cls.testdir, 'offlineimap.conf'))], shell=False)
    except subprocess.CalledProcessError as e:
        return (e.returncode, e.output.decode('utf-8'))
    return (0, output.decode('utf-8'))
