local project node paths not included

This is related to concurrently 3.0.0 and the change to use spawn-default-shell.

Previously, the path to the local node_modules/.bin were added to the path, so in my case `/users/david/myproject/node_modules/.bin:` was added to the path. This allowed concurrently to find dependencies not installed globally.

Since the paths npm/node added are not part of the shell created by spawn-default-shell, locally installed node_module dependencies are failing with `Command not found.`

Start by reproducing the failure described with concurrently 3.0.0, spawn-default-shell, and a dependency installed only in local node_modules/.bin. Trace how the npm/node PATH reaches the spawned shell; done means locally installed commands are found without requiring global installation.

Written by the indexing model from the issue text.