Switch to ast.literal_eval for dict parsing

Due to  some test data in the BDD feature files includes Python raw strings and escape sequences that standard json.loads() cannot parse switching to safer Python literal evaluation
for converting string representations of dictionaries.

test/bdd/utils/place_inserter.py

@@ -7,7 +7,7 @@
 """
 Helper classes for filling the place table.
 """
-import json
+import ast
 import random
 import string
 
@@ -52,7 +52,7 @@ class PlaceColumn:
         elif key.startswith('addr+'):
             self._add_hstore('address', key[5:], value)
         elif key in ('name', 'address', 'extratags'):
-            self.columns[key] = json.loads('{' + value + '}')
+            self.columns[key] = ast.literal_eval('{' + value + '}')
         else:
             assert key in ('class', 'type'), "Unknown column '{}'.".format(key)
             self.columns[key] = None if value == '' else value