better formatting of heroku logs, separation with large build output

Prune any past devDependencies, if present in cache

Fixbower status

unset GIT_DIR

If the --production flag is specified, this command will remove the packages specified in your devDependencies.

https://www.npmjs.org/doc/cli/npm-prune.html

npm reverted to a backwards compatible cert

broken link to CONTRIBUTING.md

not saying this line should be removed necessarily, but it is broken. Is there a good `CONTRIBUTING.md` file we could add in here? Maybe from another buildpack?

the specified node runtime should be prior in the path

npm cert bug