On chapter 7, Systems, Contexts Paths and Locations.

new file:   src/main/resources/application.conf
new file:   src/main/scala/zzz/akka/LeadFlightAttendant.scala
modified:   src/main/scala/zzz/akka/avionics/Avionics.scala
modified:   src/main/scala/zzz/akka/avionics/EventSource.scala
new file:   src/main/scala/zzz/akka/avionics/FlightAttendant.scala
modified:   src/test/scala/zzz/akka/EventSourceSpec.scala
new file:   src/test/scala/zzz/akka/FlightAttendantSpec.scala