Add Stage 0 finishers listing template & link it from friends app task

We have first finisher. Time to establish a list of Stage 0 finishers.

The list will help

to know finishers and probably adjust course offline stage start date
to know whom to conduct interview with in the first place
to take badges into consideration if any
to endorse those who finished all tasks including optionals with a badge
have a source for the offline stage course students list, built by students themselves

Please, review and suggest improvements.

kottans / frontend