Check preorders and allow register after page reload

Steps to reproduce:
- find domain that is not taken. eg: `https://btc.us/get/xyzabc.btc`
- send a preorder transaction.
- reload the page.
- now you'll need to preorder again in order to register the domain name.

Expected behavior:
The user should be shown the pre-order the transaction, mark it as completed and allow the user to broadcast (register) the domain name to the network.