Merge pull request #92 from iampersistent/master

refactor Identifiers in Products
Merge pull request #93 from iampersistent/master

add Brands
Merge pull request #94 from iampersistent/master

move SpecificationInterface out of core
force v taxonomy strong dependency because of usage in an interface
Merge pull request #97 from cordoval/patch-5

force v taxonomy strong dependency because of usage in an interface
add Owner to BaseOrder
create test PaymentProfile class
removing Cart
updates for price in Item
set/getPrice in Order
add price test for item, additional tests for price in order
updates to BaseOrder, PaymentRequest and Transaction
move order states into their own class
persist transactions instead of payment profile
add TransactionInterface
add createdAt & updatedAt