Add a Total field to the new order page, calculate and update it

Thankfully, the update to the Total textfield does not recursively fire the change event, again.
Only show order confirmation dialog when it is within 5% of current price

Test Plan:
Login and navigate to /homepage/new-order
Place an order with a target price >5% different from current buy/sell price
- No confirmation dialog

Place an order with a target price <=5% different from current buy/sell price
- Confirmation dialog is shown.
Merge pull request #3 from MattFaus/master

Add Total field and calm-down the confirmation dialog on New Orders page