Properly zeroing json objects obtained from functions

[clauderobi]

JSON object returned by functions are using jansson at the low level. This library uses malloc and free but offer the ability to override them when memory cleansing is necessary (to clean sensitive data).

Jose itself uses a rather simple zero function to clean some of the memory and then calls free. This is true even for objects originally allocated by jansson (probably indirectly). This prevents to use custom functions with jansson.

It is possible to update JOSE to use the proper way provided by jansson to handle memory cleansing?