Remove moby-dick project, update rest url

If we are changing the URL structure for projects etc., I think we should keep the plural "projects" for summary data about all projects, and use the singular "project" for URLs for a specific project.
The reason for this is it avoids the problem of name collisions between project slugs and specific endpoints. For example, if we had an endpoint for getting the maintainer names for all projects like /projects/maintainers, it would not work if someone made a project with slug 'maintainers'.

For summary data about all projects:
 - `projects` (list of all projects)
 - `projects/<something>` (something for all projects, e.g. stats)

For single projects:
 - `project/<project-slug>`
 - `project/<project-slug>/versions` (list of all versions for the project)
 - `project/<project-slug>/version/<version-slug>` (single version)
 - `project/<project-slug>/version/<version-slug>/docs` (all documents in the version)
 - `project/<project-slug>/version/<version-slug>/doc/<doc-id>` (single document)