Ignore package-lock.json by default

[kategengler]

We should run with --no-shrinkwrap by default on npm install, which ignores npm-shrinkwrap.json and package-lock.json and does not generate package-lock.json

We did this with yarn, because for most uses of ember-try, we want the scenarios to get the latest of the packages available and version drift is sometimes necessary for the changes made in the scenarios to even work.

[rwjblue]

I thought we do this already?

[kategengler]

No? We do it for yarn.