PIM-1711 Added PhpSpec dependency
PIM-1711 Run phpspec during phpunit build target
PIM-1711 Created a bulk product reader

Product reader now reads products one by one
Bulk product reader reads all products at once
Added phpspec contribution checks
Merge pull request #640 from akeneo/feature/pim-1711

PIM-1711 Return products one by one in the product reader