Refactor Gemfile

Just skinned comments and removed Sdoc gem.
Add Testing gems & Twitter Bootstrap gem.

- RSpec & Capibara to Unit Tests and Integration Tests.
- Twtter Bootstrap to responsive layout and custom CSS.
- FactoryGirls fixtures replacement.
- Misc gems.
Run Rails Layout generator.

This overwrite application and layout generated
with the scaffold and integrates Twitter Bootstrap
to them.
Run RSpec generator
Scaffold Customer model
Scaffold 'Charge' model.
Add test to resquested attributes

Test requested attributes on Customer and Charge models.
Check associations

Test and implement associations
between Customer and Charge models.