Added rich text support for items and line items
Display optional line items
Fixed invoices attachments downloads
Fixed and updated translations
Correctly handles optional line items
Only displays the toggle optional menu on quotations and purchase orders
Set optional value to false by default
Improved CKEditor integration
Add forgotten sass file
Merge branch 'feature/optional_line_items' into develop

Conflicts:
	www/webapp/locale/fr/LC_MESSAGES/django.mo
	www/webapp/locale/fr/LC_MESSAGES/django.po
	www/webapp/static/webapp/js/app/components.coffee
	www/webapp/templates/webapp/handlebars/invoicing/invoiceBase/partials/edit/lineItems.hbs
	www/webapp/templates/webapp/handlebars/invoicing/item/itemEdit.hbs
Normalize simpleEditor view like other form elements
Handle embedded relationships on the DownPaymentInvoice model
Upgrade CSS: line handles and menu are now aligned to top