Fix race condition when claiming a prize

[rickyrombo]

Naive polling fix to account for race condition where the post request is made before indexing completed.

1. Add a timeout to the request context (arbitrary 10s)
2. Poll for the balance change (arbitrary 200ms delay)
3. Move the prize already claimed check to after the polling (now realizing this doesn't matter, but w/e)

[raymondjacobson]

need rebase i think