Add support for REDIS_REPLY_STATUS in nested JSON (#189)

When strings are added as elements of an array but typed as
REDIS_REPLY_STATUS instead of REDIS_REPLY_STRING, Webdis encodes them as
nulls. REDIS_REPLY_STATUS should only be encoded as [true, str] or
[false, str] when this is a top-level status response, not an array
element. In these cases we only need the string.

Fixes #188

src/formats/json.c

@@ -151,6 +151,7 @@ json_expand_array(const redisReply *r) {
 	for(i = 0; i < r->elements; ++i) {
 		e = r->element[i];
 		switch(e->type) {
+		case REDIS_REPLY_STATUS:
 		case REDIS_REPLY_STRING:
 			json_array_append_new(jlist, json_string(e->str));
 			break;