Error in package metrics: contributors count

[lwasser]

When we are parsing contributor count, I'm noticing an upper limit of 30 in our data. I double checked and some of these packages definitely have more than 30 contributors. I suspect there is a pagination step that isn't happening when we grab contributors for a package from github's api leading to an incorrect upper bound on the data!

[lwasser]

this pr - began to address the issue
Essentially by adding per-page = 100 we allow for max returns in a single page. but because some packages have more than 100, we still need to paginate the results.

#292 (review)

I thought i had added pagination but it's obviously not working as expected. let's merge the existing pr as it will make things a bit better but we still have m ore work to do on this issue.