Changes

Tsk 26 - Clears the Story entity
Clears the Story entity removing the readCount attribute to sustitute by
a new entity called "Reading" which relation the readings of a day with
a microstory. The change affects to the entity Story, its tests and the
SQL, XML and Dataset file to clear the attribute readCount. The method
findMostReaderStoriesByGenre of the StoryDataset is modified to adapt to
the service layer because this layer will be modified in the nexts tasks
to adopt another most reading protocol