This adds a new local package called '@pegjs/publish-dev' that will be run by the CI after all other tasks.
'@pegjs/publish-dev' will, as the name implies, publish a new release of pegjs on NPM under the dev tag.
Travis was failing with a weird ESLint error, and when I checked locally, the problem seemed to be related to Vuepress v0. Upgrading to Vuepress v1-alpha seems to fix this (at least on my machine...)