Trivial Description
When requirement checks inside `MLibUtils.fastSquaredDistance` are not met a non useful exception is thrown
```
Caused by: java.lang.IllegalArgumentException: requirement failedCaused by: java.lang.IllegalArgumentException: requirement failed at scala.Predef$.require(Predef.scala:212) at org.apache.spark.mllib.util.MLUtils$.fastSquaredDistance(MLUtils.scala:508) at org.apache.spark.mllib.clustering.EuclideanDistanceMeasure$.fastSquaredDistance(DistanceMeasure.scala:232) at org.apache.spark.mllib.clustering.EuclideanDistanceMeasure.isCenterConverged(DistanceMeasure.scala:190) at org.apache.spark.mllib.clustering.KMeans$$anonfun$runAlgorithm$4.apply(KMeans.scala:336) at org.apache.spark.mllib.clustering.KMeans$$anonfun$runAlgorithm$4.apply(KMeans.scala:334) at scala.collection.MapLike$MappedValues$$anonfun$foreach$3.apply(MapLike.scala:245) at scala.collection.MapLike$MappedValues$$anonfun$foreach$3.apply(MapLike.scala:245) at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:733) at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:130) at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:130) at scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala:236) at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:40) at scala.collection.mutable.HashMap.foreach(HashMap.scala:130) at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:732) at scala.collection.MapLike$MappedValues.foreach(MapLike.scala:245) at org.apache.spark.mllib.clustering.KMeans.runAlgorithm(KMeans.scala:334) at org.apache.spark.mllib.clustering.KMeans.run(KMeans.scala:251) at org.apache.spark.mllib.clustering.KMeans.run(KMeans.scala:233)
```
This is happening in the following lines. Please add more useful information to the error message when the requirements are not met https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/mllib/util/MLUtils.scala#L537-L538
Example:
```
require(v2.size == n, s"Both vectors should have same length, found v1 is $n while v2 is ${v2.size}")
require(norm1 >= 0.0 && norm2 >= 0.0, "Both norms should be greater or equal to 0.0, found norm1=${norm1}, norm2=${norm2}")
```
