Mongodb types

I created two types for doctrine mongodb. dough_money and dough_currency_money. I put the registration for the types into the DoughBundle. As a side note, I have also created a additional types for dealing with arrays of money for use in Vespolina. To me it would be appropriate to have them in Dough, but I'll let you decide that. Here's the code https://github.com/vespolina/VespolinaPricing/tree/master/lib/Vespolina/Pricing/Doctrine/ODM/MongoDB/Type If you think it belongs here, I'll move it and put in a PR.