Adjust Stats UI

[wgranger]

The stats that are currently collected on the landing page are off and need to be adjusted. In the meantime, we can link to the project builder stats page which have accurate stats, possibly in the navbar.

UPDATE (1/22/2018): Stats should be reconsidered/reintroduced once subject set selection occurs.

[wgranger]

The main issue here is that we are currently collecting a sort of cumulative stats from each workflow (individual, collaborative, and gold standard) that is misleading. Also, classification count is returning "0" for some reason.

For now (until we choose which is better between collaborative/individual after the split) the "Feedback" tab on the project nav will be replaced with "Stats" leading to the link above, and the current stats will be hidden. This is to be done after second beta is finished.