Fixing the "newest projects" method and adding the ability to connect through a proxy for debugging

Hey @markolsen, thanks for making this gem! And for the explanation of how you explored Kickstarter's API. 

Your gem is a great starting point for me for a project I'm working on. I'm going to add some functionality (and maybe error checking) to it, and I thought I'd share any changes that would be universally helpful.

This first pass fixes the "newest projects" method, which I'm assuming was broken sometime in the last couple months because Kickstarter changed their url for it. 

And for the sake of debugging and seeing what Kickstarter is returning, I added the ability to specify a proxy to connect through (ie. Charles running locally).

I can squash the commits if you'd like. Just let me know. Thanks!

Ben