Accept only-one-sample per project as input to QuaC

QuaC fails when only one sample in input ped file (#34 (closed)). This MR fixes this issue by removing filepath globbing. This MR further adds a system-level testing to capture such errors in future (#35 (closed)).

.test/configs/project_1_sample.ped

 #family_id	sample_id	paternal_id	maternal_id	sex	phenotype
-unknown	A	-9	-9	-9	-9
-unknown	B	-9	-9	-9	-9
+unknown	A	father_1	mother_1	-9	-9