Creation of activerecord for OC (#2721)

* Creation of activerecord for OC

* Update activerecord.oc.yml

config/locales/activerecord.oc.yml

+oc:
+  activerecord:
+    errors:
+      models:
+        account:
+          attributes:
+            username:
+              invalid: solament letras, nombres e tirets bas
+        status:
+          attributes:
+            reblog:
+              taken: de l’estatut existís ja