Add valgrind tests and fix memleaks

mfapi/apicalls/file_get_links.c

@@ -19,6 +19,7 @@
 
 #include <jansson.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "../../utils/http.h"
@@ -58,6 +59,8 @@ int mfconn_api_file_get_links(mfconn * conn, mffile * file, char *quickkey)
     retval = http_get_buf(http, api_call, _decode_file_get_links, file);
     http_destroy(http);
 
+    free(api_call);
+
     return retval;
 }