Bulk insert of images on ElasticSearch

Hi guys,

First of all, thanks for this library. I came across with it today and it's amazing.

Inspecting the source code I see that, when storing images on ElasticSearch, images' signatures are calculated beforehand and then stored on the database via the method ses.add_image().

I wonder if this could be an inconvenient in order to implement some kind of bulk insertion of images on ElasticSearch, so that insertion can be done faster for a bigger set of images instead of one by one.