send "Voxbox restarting" message to front end via API

[surfacescan]

The goal is to alert the voxbox clients that the box is going down for a restart and should come back in 30 seconds. On the UI there can be a countdown timer and some kinda cool giphy :)

This is obviously fired whenever the signal is received from:

• Voxbox frontend admin section
• Central Voxbox administration panel (azure)
• via command line on the backend via ssh session