Create a new Item from a data stream.

        :param repo: Repo object.
        :param name: Name of item.
        :param data: Data stream.

        :return: New Item class instance.

def from_string(self, repo, name, string):
        """
        Create a new Item from a data stream.

        :param repo: Repo object.
        :param name: Name of item.
        :param data: Data stream.

        :return: New Item class instance.
        """
        try:
            log.debug('Creating new item: %s' % name)
            blob = Blob.from_string(string)
            item = Item(parent=repo, sha=blob.sha, path=name)
            item.blob = blob
            return item
        except AssertionError, e:
            raise ItemError(e)