components/<user>-<repo>@<version>

References: 

- https://github.com/component/component/issues/104
- https://github.com/component/component/issues/312
- https://github.com/component/component/issues/442

using `@` here because i think things will become confusing with non-version tags like:

```bash
component-installer.js-generator
```

More distinct if we do:

```bash
component-installer.js@generator
```

do folders handle `@`s though?