Fix finding boost on appveyor
Fix finding boost on appveyor

NicoHaui/SuperTeacher,NicoHaui/SuperTeacher,BFH-E1D-2015-2016/SuperTeacher,NicoHaui/SuperTeacher,BFH-E1D-2015-2016/SuperTeacher,LarsAeschlimann/SuperTeacher,LarsAeschlimann/SuperTeacher