Try to reduce number of queries

[dkarchmer]

Right now, we always first make a query to get a page_size=2 which is intended just to give us a total count, so we can compute how many pages we will need.
Few possible optimizations:

1. Always get the first page anyway, and then if needed, fork the rest of the pages
2. If lastn is passed, and it is less than say, 2000, just make a single call with page_size=2000
3. Add server API to get count (to make db query to only get count, which is faster)