Check if the user already is allowed to used the resource before adding it to the relation (fix problem adding duplicated user exception)
Check if the user already is allowed to used the resource before adding it to the relation (fix problem adding duplicated user exception)

rockneurotiko/wirecloud,rockneurotiko/wirecloud,jpajuelo/wirecloud,rockneurotiko/wirecloud,rockneurotiko/wirecloud,jpajuelo/wirecloud,jpajuelo/wirecloud,jpajuelo/wirecloud