[SPARK-4797] Replace breezeSquaredDistance

This PR replaces slow breezeSquaredDistance. A simple calculation involving 40000 squared distances between the vectors of 20000 dims shows:

* breezeSquaredDistance:  ~12 secs
* This PR: ~10.5 secs


scala style: Use "{" for multiline foldLeft argument.  No need to enclose right-hand side of "=>" with braces "{}".
```
squaredDistance = v1.toArray.zip(v2.toArray).foldLeft(0.0){ (distance, elems) =>
  val score = elems._1 - elems._2
  distance + score * score
}
```