The TP-LINK HS100 is a wifi plug that can be controlled with an app, apart from that I couldn't find anything else on how to control the plug with a programme. I was able to trace the communication and write a shell script [1] which can switch the plug on and off. If anybody is interested in merging this into fhem please feel free to do so.
[1] https://github.com/ggeorgovassilis/linuxscripts/blob/master/tp-link-hs100-smartplug/switch-plug.sh