Bootstrap project structure

[onbjerg]

We should start filling out the repository with some code.

Since the registry project encompasses multiple smaller projects (an SDK, wallet integrations and the registry itself) I think it would be good to use this as a monorepo, where one of the underlying projects is based off of aragon-buidler-boilerplate, such as:

├─ README.md
├─ LICENSE.md
├─ package.json
├─ projects
│└── registry/
│└── sdk/
│└── integration-metamask/
│└── integration-frame/