Update SPMediaKeyTap to 3b9f97c

Commit in pull request currently.
https://github.com/nevyn/SPMediaKeyTap/pull/27
Add PC keyboard keystrokes to SPMediaKeyTap delegate. Fixes #122.

The issue is simply that on the Mac NX_KEYTYPE_FAST (keycode 19) is
what the "Next song" key is. On most non Mac keyboards the "Next
song" key is actually NX_KEYTYPE_NEXT (keycode 17).

Commit tested on a CoolerMaster Storm QuickFire Rapid:
http://www.amazon.com/Storm-QuickFire-Rapid-Tenkeyless-Mechanical/dp/B0068INSUM

See the defines here (Search for NX_KEYTYPE_PLAY):
http://www.opensource.apple.com/source/IOHIDFamily/IOHIDFamily-86.1/IOHIDSystem/IOKit/hidsystem/ev_keymap.h