Remove libconfig++ installation from travis settings
Remove libconfig++ installation from travis settings

alexkernphysiker/j-pet-framework,alexkernphysiker/j-pet-framework,JPETTomography/j-pet-framework,JPETTomography/j-pet-framework,alexkernphysiker/j-pet-framework,JPETTomography/j-pet-framework,alexkernphysiker/j-pet-framework,alexkernphysiker/j-pet-framework