…rdoc renderings in ruby 1.9.3
This will fix the problem on the CI server, where some time the change occurred by "write_file" will not trigger Rubinius to generate a compiled .rbc file.
… rake task
…ns that could be written include generating thumbnails on the fly for different thumbnail sizes, or delaying the thumbnail generation until it is first called.
… `validates_attachment_presence` Fixes #631