New constructor for MultiScrubber that would take a collection of Scrubber

Current constructor for `MultiScrubber` is not very easy to use.

Adding a new one could ease things:
```java
public MultiScrubber(Collection<Scrubber> scrubbers) { 
  // ...
}
```

Or even:
```java
public MultiScrubber(Scrubber... scrubbers) { 
  // ...
}
```