add comments and clean up code;
refactor didSelectRowAtIndexPath method with switch method in Swift;
refactor numberOfRowsInSection method with switch method in Swift;
update to use Swift's implicit variable declaration and new info retrieving syntax for cells;
add asynchronous calls to download images;
refactor cellForRowAtIndexPath method with switch method in Swift;
replace UIAlertView with UIAlertController, which allows more freedom on specifying how the alert looks like;