Contacts: cleanup OC_L10N usage

apps/contacts/ajax/addbook.php

apps/contacts/ajax/addcard.php

apps/contacts/ajax/addcontact.php

apps/contacts/ajax/addproperty.php

apps/contacts/ajax/chooseaddressbook.php

apps/contacts/ajax/contactdetails.php

apps/contacts/ajax/createaddressbook.php

apps/contacts/ajax/deletebook.php

apps/contacts/ajax/deleteproperty.php

apps/contacts/ajax/editaddressbook.php

apps/contacts/ajax/importdialog.php

apps/contacts/ajax/loadphoto.php

apps/contacts/ajax/messagebox.php

apps/contacts/ajax/savecrop.php

apps/contacts/ajax/saveproperty.php

apps/contacts/ajax/showsetproperty.php

apps/contacts/ajax/updateaddressbook.php

apps/contacts/ajax/uploadphoto.php

apps/contacts/appinfo/app.php

apps/contacts/templates/part.addcardform.php