Dabbu Files API Server v1.6.2

Renamed everything to Files API Server, refactored to adhere to Files API Specification

Latest commits:
fix: rewrite check for port passed as argument
refactor: rename Dabbu Server to Dabbu Files API Server
fix: add util function to generate URL for cache api
fix: add util function to generate URL for cache api
refactor: refactor server to have routes
docs: update Procfile to disable hard_drive provider on hosted instance
docs: add documentation link to README
fix: change providerNotEnabled and methodNotImplemented http response