PEP8 openbazaar.py through ws.py

PEP8 clean up 3 of 3.  Orders.py has some very deeply nested dictionaries which necessitate long lines.  This situation may suggest minor future refactoring of the affected methods.
This code is weird but it's none of your fault: It checks if `'item_price'` is in `_order` but accesses `_order['item_price']` regardless. So, drop the `if` and the backshlash.