Update comment in offline_asset_paths.rb for newer versions of Rails

[kevinburkeomg]

The comment describes what I want to do, but the code example does not work for recent versions of Rails.

# Rails Asset Patch extension used to write assets out an offline asset directory
# for future use
# example:
#   ActionView::AssetPaths.send :include, JasmineRails::OfflineAssetPaths

It looks like that ActionView::AssetPaths was removed after Rails 3. I'm hunting around in the docs to try to figure out what the replacement was/is.