Remove a non-usued ecommerce user class scalar configuration node

Fix documentation

Remove space

Add missing documentation for SonataInvoiceBundle

Remove double antislashes
Added DebugPayment
Merge pull request #52 from sylvaindeloux/SONATA-171

Added DebugPayment
Put product main image back (and keep gallery)
Merge pull request #51 from eko/develop

Remove a non-usued ecommerce user class scalar configuration node