Support copy action

[tomaskraina]

By implementing the following methods from UITableViewDelegate protocol:

// Copy/Paste.  All three methods must be implemented by the delegate.
optional public func tableView(tableView: UITableView, shouldShowMenuForRowAtIndexPath indexPath: NSIndexPath) -> Bool
optional public func tableView(tableView: UITableView, canPerformAction action: Selector, forRowAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?) -> Bool
optional public func tableView(tableView: UITableView, performAction action: Selector, forRowAtIndexPath indexPath: NSIndexPath, withSender sender: AnyObject?)