Copy unhandled files to output directory.

For my workflow, when using the -o option, it's useful to copy all otherwise unhandled files to the output directory.

For example, with:

    watcher -o public assets

Old behavior:

    assets/          public/
     file1.coffee =>  file1.coffee
     file2.js

New behavior:

    assets/          public/
     file1.coffee =>  file1.coffee
     file2.js         file2.js

There is no effect if the -o option is not used.