test and implementation for skipping replacement of npm

test and implementation for skipping replacement of npm if requested version matches bundled version

New announcement

Warn old npm

more specific tests

test and implementation for dynamically-created Procfile support

run npm install even with prebuild node_modules

indent npm output

Merge yoga

test for pre and postinstall scripts with checked in modules, cleanup

add missing cache tests, detect server.js directly

avoid semver.io domain

renamed DISABLE_BUILD_CACHE to NODE_MODULES_CACHE

test for NPM_CONFIG_OPTIONAL and debug output for all npm config vars