Merge branch 'master' into ab-debian

Merge branch 'master' into ab-debian

* master: (109 commits)
  mongodb_plugin: makesfiles update
  mongodb_plugin: python README update
  varnish_plugin: remove from conf file not ascii characters
  elasticsearch_plugin: code optimization
  create health directory in lib directory if it does not exist
  disable streaming by default
  better text
  add mirrored hosts to the my-netdata menu
  added comments and information at backends.c
  netdata-installer.sh now uses apps.plugin -t option to test if it is capable of reading /proc files
  added option -t to test if it has the permissions to read /proc/PID/io files
  remove obsolete permissions fixup for apps.plugin from the makefiles; fixes #1789
  re-arrange colors on CPU charts on freebsd; #1842
  added twitter on README.md
  web_log_plugin: requests per http version chart added
  apps.plugin: added calls counter and isolatored file counter only to new files processed; #1827
  mongodb_plugin: locks acquireCount charts added
  updated configs.signatures
  when not running as root, get the username we run as
  fixed wrong name of old config option
  ...