== Problem: Behavior in low-space conditions ==  #7587

Situation:

  Sugar users in Uruguay are filling up their writable partitions to the point
  of ENOSPC. Rainbow may fail for a variety of reasons in such an environment.

Thoughts:

  Rainbow opens or creates a variety of files both during startup and during
  activity launch. These files include:

    - the /var/log/rainbow log file.
    - the /var/run/rainbow.pid pid file.
    - the activity log files
    - the various spool entries associated with an activity launch

  It's probably safe to make the log files and the pidfile optional. For the
  time being, I'm going to ignore errors that occur while they are created on
  the theory that doing does not presently compromise any security goals and is
  simple.

  The downside that I presently see is that I'm less likely to learn that an
  environment exists in which Rainbow was unable to open the files described
  above.

  Another downside is that our security goals might change in the future in
  ways that invalidate the theories described above.