Fix for empty string console params.

```scala
  case Some(value)                => setter(converter(value))
  case None if args.boolean(name) =>
      //hack-fix for empty string parameters, e.g. --input-null-string ""
      //scalding.Args treats "" as empty value, it's simply dropped
      
      //more technically: here we satisfy (args.optional(name) == None && args.boolean(name) != None)
      //it means args.m.get(name) == List(). Since it's not boolean parameter we know there was an attempt to set
      //a parameter with some value, but the value is now missing.
      setter(converter(""))
  case None                       =>
    default match {
      case Some(defaultValue) => setter(defaultValue)
      case None               => s:SqoopOptions => ()
    }
```