check npm incompatibility

margins around warning

combined if

tests and implementation for using yarn in place of npm

leave node_modules for caching

use pure-lockfile

use semver.io service to resolve yarn engines

restore original yarn.lock after yarn install

use mktemp compatible with both osx and linux

use yarn check before a --pure-lockfile

use yarn check before a --pure-lockfile

remove yarn check, does not work as documented

clear prebuilt node_modules for yarn users

initial implementation for bin/test and bin/test-compile

changelog for v91

remove hard max of 32 processes

remove debugging log for devdeps

Extended warnings

correct GitHub capitalization

remove npm prune to work around shrinkwrap issues

output stream errors should not fail the build

test and implementation for blacklisting LANG; fixed failure tests

only test cedar-14 by default

Updating image to align with marketing

updating the buildpack image to align better with marketing (and fix the code block in the background)

Fiznool master