Charles, Snipcart co-founder here. As mentioned by the end of the post, we're actively looking to expand our analytics game a bit. Piwik seems like a good place to start, so thanks for sharing. Cheers!
Also, please consider adding your Google Analytics use to your privacy policy. They require it, even though most people ignore this requirement and there is no enforcement.
Side note, I just tried @ replying to your companies post on Twitter and got a @your account may not be allowed to perform this action' http://i.imgur.com/9uoEn9B.png Strange, never saw that before...
That's an important point; I'm seeing referral spam in my GA reports which I never noticed before 2015. I manually discount it when compiling reports, and my understanding is that these spammers hit GA UAs at random without even loading your website.