v0.5.2: Bug-fix release

This is a bug-fix release for several minor issues which have been found in the preceding
release (0.5.1).

• Fix logging failure after log buffer becomes full.
• Fix readiness-fd notification not immediately updating service states.
• Fix use of old settings in sample configuration for Linux.
• Re-create control socket file node if it "disappears". Should solve issues if root filesystem
  is mounted read-write on boot.
• Fix potential issue with service launch failure for services using a fixed notification fd.