Write cache files after getting CurlMulti response
Write cache files after getting CurlMulti response

* If "use_cache" is enabled, write the content of each CURL response to
a temp file which stores the content and expire timestamp as JSON
* Move option-based JSON decoding of CURL response strings to later in
the process, must cache raw results in case output format changes

mariten/www-jeff,mariten/www-jeff