use-generators

Use generators packaged in gems instead of overriding resources

### Changes:
* use provided generators instead of remote resources (jasmine-rails, guard-jasmine-rails)
* add guard terminal notification integration
* reorganize Gemfile once complete via bundler-reorganizer

### Testing

```bash
$ export TEMPLATE_BRANCH=use-generators && \
rm -rf myapp && \
rails new myapp -m https://raw.github.com/thegarage/thegarage-template/use-generators/template.rb
```