fix rake commands to work in development mode on linux (no sudo)

`npm` and `bundle` required root privileges, making the install scripts unusable on my system. These specific issues are fixed by the other line changes.

This particular line change makes no immediate difference, as there's no current case where our development workflow requires root privileges on desktop Linux (and not OSX) to manipulate system-level services. It does, however, clarify my opinion that our build script should never need to automatically acquire root-level privileges in our development workflow (outside of initial package-level installation, which our build scripts have explicitly not provided in the past).

Since you're the one actively maintaining this script and have a better idea in mind about how you plan to evolve it, I'll defer this particular change to you- as long as the fixes to `npm` and `bundle` are integrated, it will solve my blocking issue.