Fixing LDAP issue with Postgres (#3033)

i18n/en.json

@@ -3499,6 +3499,10 @@
     "id": "store.sql_user.save.email_exists.app_error",
     "translation": "An account with that email already exists."
   },
+  {
+    "id": "store.sql_user.save.email_exists.ldap_app_error",
+    "translation": "This account does not use LDAP authentication. Please sign in using email and password."
+  },
   {
     "id": "store.sql_user.save.existing.app_error",
     "translation": "Must call update for exisiting user"
@@ -3515,6 +3519,10 @@
     "id": "store.sql_user.save.username_exists.app_error",
     "translation": "An account with that username already exists."
   },
+  {
+    "id": "store.sql_user.save.username_exists.ldap_app_error",
+    "translation": "An account with that username already exists. Please contact your Administrator."
+  },
   {
     "id": "store.sql_user.update.app_error",
     "translation": "We couldn't update the account"