Replace deprecated method in bancor registry

util/mergeabis.py

@@ -0,0 +1,13 @@
+#!/usr/bin/env python3
+
+import sys
+import json
+
+merged = []
+for a in sys.argv[1:]:
+    f = open(a, 'r')
+    j = json.load(f)
+    f.close()
+    merged += j
+
+print(json.dumps(merged))