makefiles/docker.inc.mk: use a variable for all volumes and environment
makefiles/docker.inc.mk: use a variable for all volumes and environment

OTAkeys/RIOT,miri64/RIOT,smlng/RIOT,kaspar030/RIOT,miri64/RIOT,toonst/RIOT,x3ro/RIOT,OTAkeys/RIOT,toonst/RIOT,aeneby/RIOT,josephnoir/RIOT,toonst/RIOT,rfuentess/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,basilfx/RIOT,mfrey/RIOT,RIOT-OS/RIOT,ant9000/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,toonst/RIOT,OlegHahm/RIOT,aeneby/RIOT,basilfx/RIOT,toonst/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,mfrey/RIOT,rfuentess/RIOT,jasonatran/RIOT,rfuentess/RIOT,cladmi/RIOT,cladmi/RIOT,josephnoir/RIOT,ant9000/RIOT,aeneby/RIOT,cladmi/RIOT,A-Paul/RIOT,smlng/RIOT,josephnoir/RIOT,mtausig/RIOT,authmillenon/RIOT,miri64/RIOT,cladmi/RIOT,jasonatran/RIOT,x3ro/RIOT,miri64/RIOT,lazytech-org/RIOT,cladmi/RIOT,jasonatran/RIOT,basilfx/RIOT,yogo1212/RIOT,lazytech-org/RIOT,A-Paul/RIOT,mtausig/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,mfrey/RIOT,smlng/RIOT,yogo1212/RIOT,mfrey/RIOT,lazytech-org/RIOT,RIOT-OS/RIOT,mtausig/RIOT,kaspar030/RIOT,ant9000/RIOT,basilfx/RIOT,kaspar030/RIOT,A-Paul/RIOT,mtausig/RIOT,josephnoir/RIOT,lazytech-org/RIOT,aeneby/RIOT,rfuentess/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,A-Paul/RIOT,yogo1212/RIOT,yogo1212/RIOT,ant9000/RIOT,smlng/RIOT,x3ro/RIOT,A-Paul/RIOT,lazytech-org/RIOT,x3ro/RIOT,yogo1212/RIOT,josephnoir/RIOT,kYc0o/RIOT,authmillenon/RIOT,mtausig/RIOT,authmillenon/RIOT,x3ro/RIOT,OTAkeys/RIOT,ant9000/RIOT,basilfx/RIOT,authmillenon/RIOT,kYc0o/RIOT,OlegHahm/RIOT,rfuentess/RIOT,kaspar030/RIOT,kYc0o/RIOT,jasonatran/RIOT,jasonatran/RIOT,kYc0o/RIOT,mfrey/RIOT,kYc0o/RIOT,yogo1212/RIOT,smlng/RIOT,miri64/RIOT,aeneby/RIOT