'Load a user certificate from a specified directory path.
:param FilePath path: Directory where user certificate and key
files are stored.
:param unicode username: The UTF-8 encoded username.'

@classmethod
def from_path(cls, path, username):

    key_filename = (username + u'.key')
    cert_filename = (username + u'.crt')
    (keypair, certificate) = load_certificate_from_path(path, key_filename, cert_filename)
    credential = FlockerCredential(path=path, keypair=keypair, certificate=certificate)
    return cls(credential=credential, username=username)
