cmogstored 1.6.0 - minor fixes on allocation errors

There are minor robustness fixes on handling errors when
allocating memory or spawn failures on otherwise-hosed systems.
These bugfixes will not affect real users unless the system
is already hosed or in badly overtaxed, so there's no real
need to upgrade.

There are minor portability improvements and I now test under
FreeBSD 10.x.

The iostat test cases are relaxed a bit to account for
virtualized devices (as iostat is less useful with modern

17 changes since 1.5.0 (Nov 2015):
      Rakefile: add missing <div> for Atom feed
      test/pwrite-wrap: remove unused variable and comment
      test/pwrite_wrap: squelch unnecessary output
      test/pwrite_wrap: reduce space overhead required
      update copyrights for 2016
      build-aux/txt2pre: drop CGI.pm requirement
      stdin is always redirected to /dev/null
      minor vfork/fork safety fixes
      process: try to handle OOM gracefully
      http_put: gracefully handle path allocation errors
      iostat_process: declare environ extern
      test/mgmt: relax checks for iostat mapping
      gnulib copyright update for 2016
      upgrade: avoid syslog call if execve fails
      rely on gnulib for environ portability
      INSTALL: update latest Debian stable version to 8.x
      README: stop mentioning cgit