Reinitialize prior dict when reconstructed from json

AUTHORS.md

@@ -54,6 +54,7 @@ Paul Easter
 Paul Lasky
 Philip Relton
 Rhys Green
+Rico Lo
 Roberto Cotesta
 Rory Smith
 S. H. Oh

bilby/core/prior/dict.py

@@ -168,8 +168,7 @@ class PriorDict(dict):
         for key in ["__module__", "__name__", "__prior_dict__"]:
             if key in prior_dict:
                 del prior_dict[key]
-        obj = class_(dict())
-        obj.from_dictionary(prior_dict)
+        obj = class_(prior_dict)
         return obj
 
     @classmethod