Error on duplicate emails (#136)

* Allow main debugging in development builds

* Early fail on attempting to sync multiple users with the same email

* Truncate duplicate list if greater than 3

* Revert "Allow main debugging in development builds"

This reverts commit 3b804dd959.

src/locales/en/messages.json

@@ -441,6 +441,19 @@
     "sync": {
         "message": "Sync"
     },
+    "duplicateEmails": {
+        "message": "Emails must be unique. Multiple entries pulled with the following emails:",
+        "desription": "Error message displayed when duplicate email addresses are synced. Followed by a list of duplicate emails."
+    },
+    "andMore": {
+        "message": "and $NUMBER$ more...",
+        "placeholders": {
+            "NUMBER": {
+                "content": "$1",
+                "example": "10"
+            }
+        }
+    },
     "ldapEncrypted": {
         "message": "This server uses an encrypted connection"
     },