notes:

- RSC (remote server control) module needs to:
  INSTALL:
  - set requested version
  ACTIVATE:
  - if live directory is already at required version number then do nothing / return
  - DOWN SHARD
  - INSTALL
  - wait for requested version to appear in tmp directory (may already be there)
  - switch temp directory and live directory
  - check that switch succeeded
  - UP SHARD


SPA:
parameters: root, unifier
  - patches in <root>/patch
  - next in <root>/next
  - live in <root>/live
  - file containing id of version to install <root>/patch/cfg_<unifier>_version_install
  - file containing id of version to launch <root>/patch/cfg_<unifier>_version_launch (note - this version must already be installed)
  - file containing id of installed version <root>/patch/cfg_<unifier>_version_install
  - file containing id of live version <root>/patch/cfg_<unifier>_version_install

RR:
lock file: rrBusyMarkerFileName(targetDirectory) => targetDirectory["/"]"rr_busy"

tests
	- 2 files
	- 3 patches
	- a present in 1 & 2 & 3
	- b present in 2 & 3
=> up and down version number...
=> different writing of home parameter (slashes, quotes,etc)
=> different writing of unifier (slashes, quotes,etc)