Nagios implementation

Adds compatibility to include nagios or check_mk (nagios add on) data in ispc's monitoring-module.

URL must containg /check_mk for cmk-detection to work. This makes OMD (current official cmk setup method) fully compatible. Further oldschool manual CMK-Setups are also working as long as you keep the default /check_mk (if you did not you can add an alias or simply build the correct autologin url on your own and leave login data blank)

Further a requirement is that your URL is HTTPS and using the same domain! E.g. ISPC is on panel.example.com you can have monitoring on moni.example.com but not moni.otherdomain.org. This is a browser limitation to iframes.

For Check_MK you have to use Cookie Based authentication. This is default since OMD is out... If you did not change yet, blame yourself :) Workaround: manually add Basic Auth data to the URL. I really mean not to support this.

Btw: I also plan on building a nagios plugin or some other way to check ISPC's health using Nagios but I need much more time for this so probably this will come as a request for 3.2 then.