Add support for internally public projects:
- Adds a project option similar to "Public" which will grant all
  logged-in users Reporter access to a project by default
- Users can use their SSH key for read-only access to Internal projects
- Users are not added to the project team when a project is internal
- Users can be added to the project team to change permission level or
  to gain e-mail notifications
- Shows in UI that projects are marked Internal, if not also Public
- Internal projects will show in the projects list for all logged in
  users
- Internal projects' events will show in the dashboard/group feeds
- Project dashboard All scope now contains Internal projects, Joined
  scope excludes Internal projects, new Internal scope added
- Admin can filter by Internal projects, like with Public projects