Revert "Only one instance of server can be started"
Revert "Only one instance of server can be started"

This reverts commit 6484e9814a3a540518606f552398e0b82f91ab4d.

* Fixes #1200

Howaner/MCServer,Tri125/MCServer,ionux/MCServer,guijun/MCServer,mmdk95/cuberite,Schwertspize/cuberite,electromatter/cuberite,HelenaKitty/EbooMC,Frownigami1/cuberite,mmdk95/cuberite,mc-server/MCServer,Haxi52/cuberite,birkett/MCServer,QUSpilPrgm/cuberite,mc-server/MCServer,Altenius/cuberite,tonibm19/cuberite,thetaeo/cuberite,nounoursheureux/MCServer,marvinkopf/cuberite,electromatter/cuberite,kevinr/cuberite,jammet/MCServer,nichwall/cuberite,nichwall/cuberite,QUSpilPrgm/cuberite,Fighter19/cuberite,Fighter19/cuberite,marvinkopf/cuberite,mmdk95/cuberite,jammet/MCServer,nevercast/cuberite,jammet/MCServer,mjssw/cuberite,mc-server/MCServer,Altenius/cuberite,ionux/MCServer,Haxi52/cuberite,electromatter/cuberite,HelenaKitty/EbooMC,jammet/MCServer,linnemannr/MCServer,electromatter/cuberite,nounoursheureux/MCServer,QUSpilPrgm/cuberite,johnsoch/cuberite,guijun/MCServer,guijun/MCServer,linnemannr/MCServer,marvinkopf/cuberite,kevinr/cuberite,jammet/MCServer,nicodinh/cuberite,guijun/MCServer,linnemannr/MCServer,bendl/cuberite,nicodinh/cuberite,nichwall/cuberite,nevercast/cuberite,mmdk95/cuberite,johnsoch/cuberite,Schwertspize/cuberite,nounoursheureux/MCServer,zackp30/cuberite,ionux/MCServer,Haxi52/cuberite,SamOatesPlugins/cuberite,HelenaKitty/EbooMC,birkett/cuberite,Frownigami1/cuberite,Fighter19/cuberite,birkett/MCServer,kevinr/cuberite,zackp30/cuberite,Altenius/cuberite,kevinr/cuberite,tonibm19/cuberite,thetaeo/cuberite,linnemannr/MCServer,nichwall/cuberite,nevercast/cuberite,mjssw/cuberite,Frownigami1/cuberite,nevercast/cuberite,zackp30/cuberite,marvinkopf/cuberite,nounoursheureux/MCServer,SamOatesPlugins/cuberite,Haxi52/cuberite,linnemannr/MCServer,birkett/MCServer,Schwertspize/cuberite,tonibm19/cuberite,birkett/cuberite,Haxi52/cuberite,ionux/MCServer,nichwall/cuberite,tonibm19/cuberite,SamOatesPlugins/cuberite,zackp30/cuberite,mjssw/cuberite,kevinr/cuberite,johnsoch/cuberite,electromatter/cuberite,nicodinh/cuberite,thetaeo/cuberite,mc-server/MCServer,birkett/cuberite,mjssw/cuberite,nounoursheureux/MCServer,QUSpilPrgm/cuberite,Howaner/MCServer,mc-server/MCServer,bendl/cuberite,Howaner/MCServer,Howaner/MCServer,thetaeo/cuberite,marvinkopf/cuberite,thetaeo/cuberite,mc-server/MCServer,birkett/cuberite,mmdk95/cuberite,bendl/cuberite,nichwall/cuberite,Schwertspize/cuberite,Altenius/cuberite,birkett/MCServer,zackp30/cuberite,SamOatesPlugins/cuberite,HelenaKitty/EbooMC,birkett/MCServer,nicodinh/cuberite,QUSpilPrgm/cuberite,linnemannr/MCServer,nicodinh/cuberite,zackp30/cuberite,tonibm19/cuberite,mmdk95/cuberite,mjssw/cuberite,nicodinh/cuberite,Frownigami1/cuberite,Schwertspize/cuberite,bendl/cuberite,Haxi52/cuberite,Tri125/MCServer,Fighter19/cuberite,tonibm19/cuberite,birkett/cuberite,nevercast/cuberite,HelenaKitty/EbooMC,ionux/MCServer,mjssw/cuberite,Frownigami1/cuberite,SamOatesPlugins/cuberite,electromatter/cuberite,Fighter19/cuberite,Fighter19/cuberite,marvinkopf/cuberite,QUSpilPrgm/cuberite,birkett/cuberite,Tri125/MCServer,guijun/MCServer,guijun/MCServer,kevinr/cuberite,Howaner/MCServer,Tri125/MCServer,johnsoch/cuberite,jammet/MCServer,Tri125/MCServer,thetaeo/cuberite,Howaner/MCServer,nevercast/cuberite,Tri125/MCServer,bendl/cuberite,Altenius/cuberite,johnsoch/cuberite,nounoursheureux/MCServer,birkett/MCServer,ionux/MCServer