title: Subscription to a UIButton.rx.tap located in UITableViewCell within UITableViewDataSource
body: <p>Let's say I have a <code>UIButton</code> in a <code>UITableViewCell</code>.
  After dequeuing the cell from the <code>UITableView</code> I want to subscribe to the <code>UIButton.rx.tap</code>. The issue is that if my <code>UITableViewCell</code> is dequeued multiple times, the subscriptions would retain. Currently I solve this problem by allocating a <code>Disposable</code> property in my <code>UITableViewCell</code>, setting it when the subscription is create,  and calling <code>Disposable.dispose()</code> on <code>UITableViewCell.prepareForReuse()</code>, however as far as I understand implementing features in a way that requires you to call <code>Disposable.dispose()</code> implies that you are doing something wrong.</p>
  
  <p>Is there any better way to accomplish uniqueness of the subscription without reallocating <code>UIButton</code>?</p>