Bump to latest version of readable-stream?

Hello,

Since so many people depend on your lovely npm module via webpack-dev-server, would you be open to a PR to bump your dependency on readable-stream to the latest version? There have been several improvements since v2 including removing the infamous `isArray` npm module.

Start by locating the readable-stream dependency declaration in the package manifest and checking the current published version against the latest release. Run the existing test suite before and after the update; done means the dependency is bumped without breaking the HPACK implementation or its tests.

Written by the indexing model from the issue text.