i2s tester

Revision:
0:bf80bb548613
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os.lib	Thu Feb 02 10:14:27 2017 +0000
@@ -0,0 +1,1 @@
+https://github.com/ARMmbed/mbed-os/#269f58d75b752a4e67a6a2d8c5c698635ffd6752