Future retry system, second attempt, with learnings from -
https://groups.google.com/d/msg/akka-user/IXKxs4d5Shk/9rMWcXr-j_UJ ,  
http://doc.akka.io/docs/akka/current/additional/faq.html , 
and http://doc.akka.io/docs/akka/current/general/jmm.html#jmm-shared-state 

Thanks to Viktor Klang