Added Array.isArray check during redaction

[ezimuel]

This PR fixes elastic/elasticsearch-js#2128 issue. The issue was related to the conversion of property array into object due to this check:

if (typeof value === 'object' && value !== null) {
  // ...
}

Since typeof of an Array is an object in Javascript (see here) the solution for removing Array in this condition is to use Array.isArray(), as follows:

if (typeof value === 'object' && !Array.isArray(value) && value !== null) {
  // ..
}

[pquentin]

Thanks! LGTM.