Unlike the company's Flip Leather Case, Simplism's new Shoulder Leather Case for iPad ($TBD) opens from the top rather than the side -- a bit unusual and inconvenient given that the flap sort of awkwardly bends backwards -- but has one feature that we think is going to be quite popular going forwards with iPad cases: a shoulder strap. This one looks quite like a purse strap, complete with spring-loaded claws on the ends of the strap and circular eyelets…