Update to v0.1.0

 * total rework of transcompilation-feature

 * Note that `.dart2js` templates are no longer needed. Sprockets
 DirectiveProcessor for Javascript ist now capable of including
 dart2js-compiled scripts via a `//= dart dart_app` directive. See
 updated sample application on github.

 * Errors during dart2js compilation will now be handled by Sprockets
 and thus the exception message will be thrown in the created js file.
 For now there will be also an output on the console.

 * As for newest SprocketsRails there is no longer the need of manually
 adding `dart.js` to the precompilation list.

 * Compiled scripts will reside in the `#{Rails.root}/tmp/cache/` directory.
Merge branch 'issue-#9' of github.com:m0gg/dart-rails

update to v0.1.0