Remove PID file on crash
Storio non blocking with sub threads processing disk access
>> To activate the feature
  . change src/CMakeLists.txt
    line
      add_subdirectory(storaged)
    becomes
      add_subdirectory(storaged_nb)
  . change tests/setup.sh
    lines
      #storaged_dir="storaged_nb"
      storaged_dir="storaged"
    become
      storaged_dir="storaged_nb"
      #storaged_dir="storaged"

>> Each storaged starts only one storio process. The storio process provides
   io services on the port list defined in the configuration files as in
   previous version.
   e.g: if the storaged at address A.B.C.D has in its configuration file
   ports = [ P1, P2, P1, P3 ] ;
   The storio process will listen on
     A.B.C+1.D:P1
     A.B.C+2.D:P2
     A.B.C+3.D:P1
     A.B.C+4.D:P3

>> The storio has by default 2 threads that process the disk access requests.
   Nevertheless this can be changed by setting "threads" option in the
   configuration file.
   e.g: "threads = 3;" makes the storio starts 3 disk threads.

>> A storio rozdebug command "diskThreads" provides statistics per thread
   (one thread/column + one total column).