Changes

tsk30 Adds more example data to the dataset.
Adds new data to stories.xml and updates StoriesDataset to match the new
data, also updates the getRecentStories method, to match the new data

tsk30 Updates Story to not allow User to be null and formats the date.
User cannot be null and adds a new format to date (DD/MM/YYYY HH:MM:SS) 
Adds a new dependency that allows to ignore every property that is not
defined, this allows to use the new method getDateFormated() and pass
the tests

tsk30 Changes the language of the interface to spanish and the format of
the date.
Changes the language of the interface to spanish and the format of the
date is displayed now in the new format DD/MM/YYYY HH:MM:SS.