Asset conversion process

[sheerun]

This should be extracted from rails-assets. It handles following:

• splitting assets to javascripts, stylesheets, images, fonts, and other
• generating manifest files for assets (with requires of main files)
• automatically convert relative url() to asset-url() in stylesheets (css, sass, less, styl)
• convert all .css files to .scss (for good sprockets integration)
• remove all ignored files
• remove minified versions if not minified versions are available
• remove all files in following directories: spec test perf minified docs examples min
• remove gzip, map, nuspec files

The output of this task is class:

class AssetConverter
  # @param source [Pathname] - where bower installed component
  # @param destination [Pathname] - where to save converted component
  # @raises [BoweredError] - if conversion fails for some reason
  def call(source, destination)
  end
end

Questions:

1. Any other transformations?
2. Are those transformations reasonable?
3. Should this class accept / return Pathname? It's hard to test.