Add empty custom-checks.json

custom-checks.json

+{
+    "$schema": "https://git.opendatafrance.net/validata/validata-py/raw/master/custom_checks_schema.json",
+    "title": "Validations personnalisées en complément du schéma SCDL Base d'adresses locales",
+    "author": "Pierre Dittgen, Jailbreak",
+    "version": "0.1",
+    "created": "2018-06-05",
+    "homepage": "https://git.opendatafrance.net/",
+    "checks": [
+    ]
+}