Add the 'json' package. Code taken from simplejson 1.9 and contributed by Bob
Ippolito.

Closes issue #2750.

PC/config.c

diff --git a/PC/config.c b/PC/config.c
index 0d19caf..f128382 100644
--- a/PC/config.c
+++ b/PC/config.c
@@ -54,6 +54,7 @@
 extern void initdatetime(void);
 extern void init_fileio(void);
 extern void init_functools(void);
+extern void init_json(void);
 extern void initzlib(void);
 
 extern void init_multibytecodec(void);
@@ -132,6 +133,7 @@
 	{"datetime", initdatetime},
 	{"_fileio", init_fileio},
 	{"_functools", init_functools},
+	{"_json", init_json},
 
 	{"xxsubtype", initxxsubtype},
 	{"zipimport", initzipimport},