alldos2unix should be a rake task instead of capistrano

`alldos2unix` functions perfectly well as a capistrano task, but it doesn't belong there, especially now that capistrano tasks will require a stage to be specified. Capistrano is essentially rake for remote tasks. Since this is a local task, it should just be a normal rake task. Run it with `rake alldos2unix`.

    $ rake -T
    rake alldos2unix  # Convert line endings to unix for all files under the current directory

I wanted to run this by you @akofink before I made the change.