Fix #56: Update CONTRIBUTING document with a section on writing tests
Fix #56: Update CONTRIBUTING document with a section on writing tests

Signed-off-by: Joachim Nilsson <583c295fd7602c168ad814279bbc3894ba65f5d6@gmail.com>

peda-r/libconfuse,westermo/libconfuse,westermo/libconfuse,troglobit/libconfuse,peda-r/libconfuse,troglobit/libconfuse,martinh/libconfuse,martinh/libconfuse