PlayerPage would be disabled when the last song in currentPlaylist have been removed
PlayerPage would be disabled when the last song in currentPlaylist have been removed

Change-Id: I2d9d51aaf1f3d38b11022eb2d3e34ac34d2401c7
Issue-Id: #65
Reviewed-on: http://cr.qtquick.me/243
Tested-by: http://ci.qtquick.me/
Reviewed-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>
Tested-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>
Tested-by: Takahiro Hashimoto <b59128e2582a625f3a4337ede555b631692b1b94@qtquick.me>
Reviewed-by: Takahiro Hashimoto <b59128e2582a625f3a4337ede555b631692b1b94@qtquick.me>

qt-users-jp/qumoplayer,qt-users-jp/qumoplayer,qt-users-jp/qumoplayer