Fix issue #2833 with backslash in JSON

Backslash will be removed form JSON responses for each request
and for the initial configuration request

acme.sh

@@ -2086,7 +2086,7 @@ _send_signed_request() {
 
     _debug2 original "$response"
     if echo "$responseHeaders" | grep -i "Content-Type: *application/json" >/dev/null 2>&1; then
-      response="$(echo "$response" | _normalizeJson)"
+      response="$(echo "$response" | _normalizeJson | _json_decode)"
     fi
     _debug2 response "$response"
 
@@ -2503,6 +2503,7 @@ _initAPI() {
       _err "Can not init api."
       return 1
     fi
+    response=$(echo "$response" | _json_decode)
     _debug2 "response" "$response"
 
     ACME_KEY_CHANGE=$(echo "$response" | _egrep_o 'key-change" *: *"[^"]*"' | cut -d '"' -f 3)