updated for mbed-os 5.5

Fork of Task121 by Nicholas Outram

Revision:
4:612f8694a6e8
Child:
10:c75a585e57a7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed_app.json	Tue Sep 10 13:23:09 2019 +0000
@@ -0,0 +1,3 @@
+{
+    "requires": ["bare-metal"]
+}
\ No newline at end of file