add total field as money to invoices
spec cleanup and begin Invoice Builder Service
Add Topic as scope to aggregate invoice/entry line-items for invoice builder
Adjust topics and entries, and WIP Invoice Builder Service
Fixing up some Entry Specs
add validators to config/application.rb autoload config
make changes to new entry form to account for topic_id instead of string
Validates Entry has Invoice, adjust entry index and show
Fix up Entry Specs and factories
add Topic model
add topic factory and spec
adjust entries controller to use whitelist topic_id
Entry now belongs to Topic
merge invoice builder branch up to topic model into master