Finished writing activity function which takes into account the recent
open events more so than the older ones. Have to fine tune and add a
maximal threshold. Also have to integrate dropbox delete functionality
Integrated Dropbox Authorization. Have to now delete the file
Added JavaDoc, implemented LRU cache functionality. Tested.
Modify events don't add duplicate events. Should have fixed this earlier
Fixed bug where open events were getting deleted always. It should only do
so if the file has recalculated expiration_date