Order cards and boards (under the search bar) by modification/use date#142

I would love to be able to see the cards and boards I have been working on recently on top of the list (under the search bar). That is, ordered accorinding to the time when they were last edited or accessed. (I would keep the possibility of ordering them according to their creation date, as currently implemented though). Thanks!

This will be implemented within the scope of UI Update II