Abstract Refreshable Table View based ViewController

[gbasile]

Create an abstract ViewController with all the code necessary to implement pull to refresh.
Any VC subclassing this abstract should only declare

1. The method reloadData
2. TableView delegate
3. Table view datasource
   Let´s call this class "AbstractPullToRefreshVC

Create a subclass of this VC only for the Games. A refreshable VC with games is often shown in a lot of places in the application. Subclasses of this method should only declare

1. The method reloadData.

This refactor is necessary because in this moment we have a lot of duplicated code dues to PullToRefresh.

Another improvement is to take care to update the "last update information" of the Pull To Refresh only when we really receive a valid information from the server. In this moment it updates the date when the user execute the Pull to Refresh, whatever the information was successfully reloaded.