Remove reliance on Yapep

[maderlock]

This looked like a useful API abstraction for Vend as it covers both the 0.x and 2.x APIs. However, there's no way I'm adding the bloat of yapep_base into my non-yapep application. Is this something that could be made optional?

[emulgeator]

What you're saying totally makes sense. We are discussing the possibilities of getting rid of this dependency.