Support for other ANN libraries

[gfournier]

I'm currently working on Annoy index integration into faiss-grpc-server, source code is located here:

• fork: https://github.com/gfournier/python-faiss-grpc-server
• branch: https://github.com/gfournier/python-faiss-grpc-server/tree/annoy_index_support
• PR: Add Annoy index support gfournier/python-faiss-grpc-server#1

Are you interested in such features or do you prefer that I start a new project ?

In addition to annoy I plan to:

• create a docker image
• download remote index files (from S3 or GCP)
• sync if a new index file is posted to original URL (file, S3, GCP)
• serve multiple index files (this will break the service contract by introducing an index name in RPC methods)