Re-worked classes for trans, merch, item
changes to item, merchant, and transaction files (and tests)
added methods and refactoring to Item class
refactored item_builder.rb
edited and refactored Merchant class
changes to item and merchant class
edited Item and Merchant files
refactored transaction files
minor refactoring for item, merchant, and transaction files
Merge branch 'OO_i_m_t'
Merge branch 'master' of https://github.com/gschorkopf/sales_engine