2.6.3

Icinga2 changelog: https://github.com/Icinga/icinga2/milestone/64?closed=1

Changelog:
improve icingaweb2 director docs
Merge pull request #92 from jkrauska/master
add nrpe plugin
Merge pull request #88 from bebehei/disable-sshcheck
disable check of ssh-service on own container
Merge pull request #85 from jjethwa/dev
Update Dockerfile
Update Dockerfile
Update README.md
Merge pull request #84 from jjethwa/master
Merge pull request #83 from bebehei/shellcheck
small fixes proposed by shellcheck