Print out how many remote devices are connected

In text form for now (some, none, all).

Simplify code

Remove division by zero

If there are no remote devices, the completion is assumed to be 100.

Use API to retrieve local device ID for filtering

/rest/system/connections returns the local device as well (as
unconnected). Filtering out by connection status could falsify the
output.

CI: Add build file

Add readme

Add average over remote devices

Add licence

Initial commit