Replace numeral by sprintf-js

Both libraries are unsupprted anyway. But sprintf-js has more downloads 😀

Why should we replace the library:
1. We can format a number and add units
2. We can format a string and take only part of it

Disadvantage:
- nobody knows the syntax (or nearly)

Examples:

```
var sprintf = require('sprintf-js').sprintf;

console.log(sprintf('%s', 'abcdef')) // abcdef
console.log(sprintf('%.4s', 'abcdef')) // abcd
console.log(sprintf('%d', 123.1234)) // 123
console.log(sprintf('%d MHz', 123.1234)) // 123 MHz
console.log(sprintf('%.2f', 123.1234)) // 123.12
console.log(sprintf('%.2f', 123)) // 123.00
console.log(sprintf('%04d', 123.1234)) // 0123
```

If we replace the library we should think about settings migration.