Doesn't work with node >= 7

During installDeps.sh there are multiple deprecations:

npm WARN deprecated jade@0.26.3: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated graceful-fs@2.0.3: graceful-fs v3.0.0 and before will fail on node releases >= v7.0. Please update to graceful-fs@^4.0.0 as soon as possible. Use 'npm ls graceful-fs' to find it in the tree.
npm WARN deprecated minimatch@0.2.14: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
npm WARN deprecated minimatch@1.0.0: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue

the graceful-fs package causes etherpad to be incompatible with node >= 7.0 and causes etherpad to crash with

 module.js:474
     throw err;
     ^
 Error: Cannot find module 'internal/fs'
     at Function.Module._resolveFilename (module.js:472:15)
     at Function.Module._load (module.js:420:25)
     at Module.require (module.js:500:17)
     at require (internal/module.js:20:19)
     at evalmachine.<anonymous>:17:20
     at Object.<anonymous> (/opt/etherpad/src/node_modules/npm/node_modules/graceful-fs/fs.js:11:1)
     at Module._compile (module.js:573:32)
     at Object.Module._extensions..js (module.js:582:10)
     at Module.load (module.js:490:32)
     at tryModuleLoad (module.js:449:12)

[DocMAX]

please fix that stupid error!!!

[Gared]

NPM needs an update. My changes worked so far and I can hopefully provide a PR tomorrow.