Fail soft mode

The Fail soft mode feature permits to stop playing device content when some instability is detected (several unexpected player reboots happen in few minutes).
When the player is in Fail Soft mode,
- A specific Fail soft mode pop-up is displayed on the screen
- The green led (at the back of the player) is blinking by following a specific sequence
To return to Normal mode, new publishing is required (attention: most of time, unexpected reboots are certainly due to a specific media inserted in the playout and not supported by the player (it can be an audio-video media, or any other media), so it is advised to look for the wrong media and remove it before publishing again)
The Fail soft mode is a security feature implemented in Gekkota_os (except LCAN & EEEBOX) since Gekkota 3.12.15. For security reasons, the fail soft mode feature is automatic and can not be removed from the player

`2017-07-18` (last update)