Division-by-zero fix in RoundRobinLoadBalancerFactory when no nodes with right capability is online

Old code would send down empty list to chooseNext, which would do '% items.size', triggering ArithmeticException(/ by zero)
Test included
Bump sbt build version

Haven't gotten around to migrate to gradle yet, still using sbt.
SBT build: bumping to scala 2.8.2

This fixes an issue we've been having when two parallel threads talks
with the ClusterNotificationManager. For example, a JVM with both client
and server would have the ClusterClient call
ClusterNotificationMessages.GetCurrentNodes, but every now and then one
of the calls failed with "Received unknown message: GetCurrentNodes",
leaving the ClusterClient blocking forever.
Most likely this was due to https://issues.scala-lang.org/browse/SI-1591
which is fixed in 2.8.2

Headsup: with this "bugfix" version of scala some boxing changes seems
to have happened.. If you use scala libraries in java code, for example
Option[Long] is no longer java Option<Long> but now Option<Object>..??
Java-compat, make sure nodes are capabilities aware
Java-network: add sendRequest calls which are capabilities & maxRetry-aware.