[services] Blob - Update service implementation

Summary:
Depends on D3521

Update implementation of the blob service

Test Plan:

cd services
yarn run-backup-service

Reviewers: geekbrother, palys-swm, jimpo, varun

Reviewed By: palys-swm

Subscribers: ashoat, palys-swm, Adrian, atul, benschac

Differential Revision: https://phabricator.ashoat.com/D3471