tourney import only (WIP)

REST API done for this part, still need to write UI
@garsh0p @jhertz 

no auth integration yet; need to rebase onto master.

(other changes are still on the other branch, which I'll rebase onto this one at some point)
I don't think these assignments to `players` and `matches` are necessary. I'd rather remove it because (with these assignments) it starts out as a list of Strings and ends up as a list of ObjectIds.