Revert "Remove TS to avoid spammers."

This reverts commit 083f64d3520c8cd7b5cb3ed15076c1d6c791a99f.
Fix broken unshortener for some URLs + add test. #17
Tweak unshorten URL to treat error cases as we find them + regression tests. #17
Remove unused collections.
Use a min-max scalar in [0,1] interval.
Add weights for features, promote MI, RI only. #10
Migrate shortened URLs from db to expanded ones. #18
Show up to precision of 4 decimals. #9