copy of rtc example

Changes

RevisionDateWhoCommit message
2:b3aa9dd045be 2018-02-06 tulanthoar import to local repo default tip
1:a474ab5e98f9 2017-04-21 tulanthoar switch to mbed-os
0:32f1960de3fb 2017-04-21 tulanthoar copy of rtc example