Additional Serial Example

Revision:
0:7376f17bb36e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Jan 19 14:23:15 2017 -0600
@@ -0,0 +1,8 @@
+#include "mbed.h"
+
+Serial device(USBTX, USBRX);  // tx, rx
+
+int main() {
+    device.baud(19200);
+    device.printf("Hello World\n");
+}