Set `spec_mode` before `setup`

tl;dr it makes this possible

```ruby
Motion::Project::App.setup do |app|
  if app.spec_mode
    app.delegate_class = "SpecAppDelegate"
  end
end
```

I wanted to be able to do spec-mode-dependent actions in my `App.setup` block, but couldn't because the blocks were all run immediately *before* `app.spec_mode` was set in `project.rb`. This was because plain `App.config` triggers `setup` immediately.

This changes `App.config` to `App.config_without_setup`, so the `App.setup` blocks are run *after* `spec_mode` has been set.