Add bigDecimal converter.
Add total amount calculator with added value functionality

this commit changes default behaviour of calculating total amount in
invoices.
Refactor package name.
Fix boxed panel css width.
Add invoices report section.

this commit add the ability to review created invoices and the ability
to search by id or name.
Add the Payment domain to invoices.
seperation of creating invoices into new backing bean.
Add related methods in abstract GeneralForm backing bean.
reduce backing bean scopes.

thers isn't any ajax request into this beans and request are independent
so request scope is sufficient.