Guitar Play and Share update

Guitar gets an update which is pretty much the same as iShred.

• Alternate tunings can now be created and saved in a song. Great for Drop-D and other special tunings, or just for key transposition.
• Can now adjust the guitar's volume independent of any backing track or music player volume, making it softer or louder than before.
• Strings are now animated on faster devices (including iPhone 3GS+, iPod touch 2nd gen+, and iPad).
• Version number now shown in the Settings/About title, not on the splash screen.