Simplify the repo structure by removing the deploy directory

[36degrees]

What

Update the build directory in the Middleman config to build to /build.

Move and rename the /deploy/public to /build and delete everything else in the deploy folder.

[!IMPORTANT]
This means that the Netlify config needs to be updated, as the base directory has changed.

Add build settings to the netlify.toml file in the root of the repo so that Netlify knows which folder to deploy (but previews for existing branches and PRs without this change continue to work).

Update any other references to the deploy folder, including e.g. .gitignore

Before

.
├── config
├── data
├── deploy
│   ├── manifest.yml   # deleted
│   ├── nginx          # deleted
│   ├── nginx.conf     # deleted
│   └── public         # moved to /build
├── docs
├── lib
├── source
└── spec

After

.
├── build
├── config
├── data
├── docs
├── lib
├── source
└── spec

Why

Now that we've migrated off of PaaS, we can simplify the deploy folder, as we no longer need the CloudFoundry manifest, nginx config or mime type configuration.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• [ ] Middleman build directory updated
• [ ] CloudFoundry manifest, nginx config and mime types deleted
• [ ] References to the deploy folder updated
• [ ] netlify.toml includes updated base path