The inSender parameter of IOHIDValueCallback (input_callback) is already a HID
device.

This change fixes the detection of joystick events on Mac OS X 10.6. On 10.9 the
old code also worked, presumably because IOHIDQueueGetDevice returned the input
parameter as result in case it wasn't an IOHIDQueueRef (on 10.6 it returned
NULL)
Fixed typecast (fixes warning in previous commit, no functional change)
Modernize/fix build

 1. Update project settings.

 2. Update target to 10.7 (incompatible layout constraints were causing
    a build failure).

 3. Include the dualshock joystick image in the repo (it was missing for
    some reason).

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Merge pull request #13 from stephencelis/fix

Modernize/fix build