example creating a Ticker with callback

Revision:
1:fa1a6e600bdb
Child:
2:982ebb531653
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os.lib	Thu Jan 19 10:48:50 2017 -0600
@@ -0,0 +1,1 @@
+https://github.com/ARMmbed/mbed-os/#04a31f3b39bfbd69e155ed7c9f55880fd75278ba