Resolve "Disease code can be "\n""

Closes #1 (closed)

test/config/config-n-disease-code.json

+{
+  "samples": {
+    "16699289": {
+      "disease_code": "\n",
+      "gvcf": "test/data/16699289_chrM.g.vcf",
+      "vcf": "test/data/16699289_chrM.vcf"
+    }
+  },
+  "settings": {
+    "threshold": 10,
+    "distance": 0
+  }
+}