added code to allow failed messages from bad content url

shared/campaigns.js

@@ -53,7 +53,13 @@ const CampaignMessageStatus = {
     COMPLAINED: 4,
     SCHEDULED: 5,
 
-    MAX: 5
+    MAX: 5,
+    FAILED: 6
+};
+
+const CampaignMessageErrorCode = {
+  RETRY: 0,
+  NORETRY: 1
 };
 
 
@@ -90,5 +96,6 @@ module.exports = {
     CampaignStatus,
     campaignOverridables,
     CampaignMessageStatus,
+    CampaignMessageErrorCode,
     getSendConfigurationPermissionRequiredForSend
-};
+};