get_workers gets more than 100 workers/assignments
get_workers gets more than 100 workers/assignments

get_workers now counts the total number of results for
a given hit, and then requests multiple pages of up to 100
assignemnts per page until all results are obtained.

Note, however, that the code is currently still limited to
returning workers from the first 20 hits.

Fixes #203

suchow/psiTurk,NYUCCL/psiTurk,suchow/psiTurk,suchow/psiTurk,NYUCCL/psiTurk,NYUCCL/psiTurk