[banshee] Require OSX 10.9 as a minimum (bgo#750563)
[banshee] Require OSX 10.9 as a minimum (bgo#750563)

As evidenced by the compiler errors in bgo#750563, the 1.x current
version of gstreamer which we pull cannot be compiled in OSX 10.8.

BansheeMediaPlayer/bockbuild,BansheeMediaPlayer/bockbuild,BansheeMediaPlayer/bockbuild