general code clean-up; methods over 80 char; removing comments; tightening up 'ends'
fix conflict in app/models/invoice.rb to retain start_date instead of created_at
commented out binding_of_caller
adjusted the InvoiceService create method to work with decimals
Merge branch 'refactoring-immigrants' of https://github.com/jmejia/daughter_of_store_engine
Merge branch 'master' of github.com:jmejia/daughter_of_store_engine
fixed merge conflicts