Introduce machi_flu_psup:start_flu_package/4 as a way to start all
related FLU processes
* The projection store
* The chain manager
* The FLU itself
... as well as linked processes.
http://www.snookles.com/scotttmp/flu-tree-20150430.png shows one FLU
running, "a". The process registered "a" is the append server,
"some-prefix" for the sequencer & writer for the current <<"some-prefix">>
file, and a process each for 3 active TCP connections to that FLU.
