Add feed tamper to convert year to full date to import classes properly

#5761 

Added in this PR a feed tamper to allow using a year value "yyyy" as the date. The feed tamper extends the date to the full date and only the year value is actually used.

Output:
![selection_129](https://cloud.githubusercontent.com/assets/4497748/2849977/840a67f6-d0ee-11e3-86ff-d3af3bf57f11.png)

And the import of the class from the year 2000:
![selection_130](https://cloud.githubusercontent.com/assets/4497748/2849978/92155a2c-d0ee-11e3-85d1-ff60aaf40177.png)