adds a config class to centralize settings

that way the middleware, extension and rake tasks can all read from
the same location for settings
rounds out the configuration class

- renames to ClassyAssets::Configuration to avoid name collision with
  Rbconfig
- adds more options needed for all facets (middleware, extensions, rake)
- finalizes specs, including making sure class is reset after each spec,
  to ensure we don't have tests bleeding into each other
uses Configuration class for all options now
uses Configuration class for all options now
module responsible for importing our rake tasks

    require 'classy_assets/tasks'

will add rake assets:precompilation and rake assets:clean tasks for
projects utilizing this gem
makes use of configuration class for all options
fixes assets:clean task
Bump to 0.0.3
getting bin/.files into gem
Bump to 0.0.4
hardcodes executables in gemspec
hardcodes executables in gemspec