Added to Invoice model, default zero amounts on tax, subtotal and total columns. Added mini profile for invoices on the invoices index view.

Files Modified:

modified:   app/assets/stylesheets/bootstrap_and_overrides.css.scss
modified:   app/views/invoices/index.html.haml
modified:   app/views/layouts/application.html.haml
modified:   db/migrate/20130806190154_create_invoices.rb
modified:   db/schema.rb
Added company model
Add Facebook login
Fixed redirects