Added mozart-empty as a submodule, updated Rake tasks and versions

* Added github.com/bigcommerce/mozart-empty as a git submodule
* Added Rake task to clean existing JavaScript files from vendor path
* Chained the above to the :release Rake task
* Updated versions of assets and gem
* Updated Mozart version to 0.1.8
Merge pull request #2 from sgerrand/update-to-v0.1.8

Added mozart-empty as a submodule, updated Rake tasks and versions
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
Changes handlebars dependency, adds tests, corrects asset include, bumps version

* Changes handlebar gem dependency to handlebars_assets
* Adds includes for JavaScript library gems so they load via the asset pipeline
* Corrected mozart-all manifest to use handlebars.runtime
* Updated gem description
* Corrected usage information in generator to match README
* Added tests for gem class constants
* Bumped gem version
Added Travis-CI build configuration