Merge branch 'master' into ab-debian

Merge branch 'master' into ab-debian

* master: (75 commits)
  ipv6 metrics swapped; fixes #2000
  haproxy_plugin: get data via UrlService bugfix
  more info about -W set
  allow all configuration options to be set from the command line; #1991
  allow .scope sub-cgroups
  enable libvirt cgroups
  mongodb_plugin: take "arbiter" replica set member into account
  Create draft release when uploading from Travis
  Update checks to work on OS X
  Post release 1.6.0
  Prepare release 1.6.0
  Fix misc compiler warnings on FreeBSD
  Fix compiler warnings for FreeBSD plugin
  coverity: 164803 Resource leak in ARL (impossible case)
  freebsd coverity: 164808 Uninitialized scalar variable
  freebsd coverity: 164810 Uninitialized scalar variable
  freebsd coverity: 164802 Same on both sides
  fixed typo in sizeof()
  properly initialize new memory regions after reallocz(); fixes #1972
  run-parts does not run scripts with .sh extension
  ...