Added allowIpod to IOSApplicationConfiguration

Added a new variable to IOSAppConfig called allowIpod in order to be
able to play the game without stopping the background music from iPod
app.
Also, modified the constructor of IOSAudio to pass the
IOSApplicationConfiguration from IOSApplication.
Merge pull request #1 from libgdx/master

Update
Merge branch 'master' of https://github.com/xYaW/libgdx
Merge pull request #956 from xYaW/master

Added allowIpod to IOSApplicationConfiguration