Post ETH Online refactor

[0xjjpa]

Background

The goal of this PR is to get Poster App ready for the next steps, which include

• Allowing anyone to be able to spin a local instance of Poster App, and providing instructions on how to deploy Proxy Poster on top for local development.
• Allowing anyone to deploy an instance of Poster App, and be able to migrate from any chain at any point in time.
• Setup the required third-party tools (e.g. Infura, Pokt Network, TheGraph, Biconomy) to allow integrating with the application.
• Start with the UI overhaul and set up a UI framework to be used for social apps.

Tasks

• Migrates to xDAI, fixes #22

Additional PRs

• Subgraph: https://github.com/onPoster/subgraph/pull/6
• Contracts: https://github.com/onPoster/contract/pull/25

[0xjjpa]

Current setup now fully working locally, documentation and additional tooling to come next.