Create new listings

https://trello.com/c/lWL1o6nL/17-as-a-user-i-want-to-be-able-to-list-items-for-sale-in-the-marketplace

![image](https://cloud.githubusercontent.com/assets/8669803/5093529/30717404-6f27-11e4-9f3d-df3405fda430.png)

![image](https://cloud.githubusercontent.com/assets/8669803/5093536/47843e9c-6f27-11e4-8d0b-9bacf2a4a871.png)

![image](https://cloud.githubusercontent.com/assets/8669803/5093538/5189f710-6f27-11e4-97a2-0e8c4ad08f67.png)

![image](https://cloud.githubusercontent.com/assets/8669803/5093540/5be7d182-6f27-11e4-922f-ebc54b90adce.png)