fix(pip): update location of pip installer
fix(pip): update location of pip installer

raw.github.com URLs have moved to raw.githubusercontent.com, and
wget was seeing a 301 (Moved Permanently) under the covers. curl
does not automatically follow such a redirect, so the URL change
caused an error for deis/tester, but was benign here.

Joshua-Anderson/controller-sdk-go,Joshua-Anderson/controller-sdk-go