Pull dependencies via web, create asset manifest

* Removes git submodule for mozart dependencies
* Adds new :clean rake task to remove old dependencies
* Adds new :download rake task to pull JavaScript files from web
* Removes :copy_source_files rake task
* Adds new class file for assets related constants (not ideal)
* Adds new mozart-rails asset manifest for cleaner and tidier usage
* Adds GEM_ROOT constant
* Removes JavaScript file dependencies and replaces them with gem versions
* Updates README
* Bumps gem version to 1.0.1
Changes asset manifest to mozart-all, updates associated README and Rake tasks
Merge pull request #4 from sgerrand/minimized-assets-in-production

Pull dependencies via web, create mozart-rails asset manifest for easier usage