Move files into a new location, discarding it's previous file hierarchy

Gruntfile.coffee

module.exports = (grunt) ->
  
  # Requires a `renameBase` property in task config options.
  flattenPath = (dest, src) ->
    path = grunt.task.current.data.renameBase
    # Make files sibling to those in `renameBase`.
    if src.indexOf(path) is 0
      dest + src.slice path.length
    else
      dest + src

  grunt.initConfig
    copy:
      assets:
        files: [
          # Fonts, images, etc.
          expand: yes
          src: 'app/assets/**'
          dest: 'public/'
          renameBase: 'app/assets'
          rename: flattenPath
        ]