Simplify Jasmine::Configuration#rack_apps
Remove metaprogramming from Formatters::Multi

It’s much simpler this way.
Refactor asset expander

 * Move AssetBundle classes into same file as AssetExpander
 * Remove RailsAssetBundle superclass
 * Remove arguments that are always passed the same value
 * Prefer extending a module to instance_eval
 * Prefer flat_map to map{}.flatten
Merge pull request #210 from nertzy/refactor

Refactor Asset Pipeline handling.