RangeHandle does not properly group repair updates

[stephentu]

RangeHandle uses a

var loosers = new HashMap[Array[Byte], (Array[Byte], List[RemoteActorProxy])]

to attempt to group loser keys. however, there are several issues with this

(1) Array[Byte]'s hashcode is identity based:
scala> val h = new collection.mutable.HashMap[Array[Byte], Int]
h: scala.collection.mutable.HashMap[Array[Byte],Int] = Map()

scala> h += ((Array(0,1,2), 1))
res0: h.type = Map(([B@1224b90,1))

scala> h contains Array(0, 1, 2)
res1: Boolean = false

2. we're not even taking advantage of this, since we don't have a bulk put request, but we process puts sequentially (albeit asynchronously)
   for ((key, (data, servers)) <- handler.loosers) {
   for (server <- servers) {
   server !! PutRequest(key, Some(data))
   }
   }

so i propose either we
(1) considering the HashMaps into an ArrayBuffer for efficiency

(2) use a wrapper class around Array[Byte] which properly computes the hash code. then we can take advantage of this grouping by introducing a bulk put request

the current solution is sub-optimal compared to (1) or (2) b/c a) we don't group keys properly, b) even if we did we don't exploit the grouping

thoughts?