Remove Default Themes

```
Dir.foreach("#{new_project_dir}/wp-content/themes") do |item|
  next if item == '.' or item == '..'
  FileUtils.rm_rf "#{new_project_dir}/wp-content/themes/#{item}" if File.directory?(item)
end
```

This seemed to work at one point, but now all of the theme directories are returning `false` to `File.directory?`
