Merge branch 'master' of https://github.com/keystonejs/keystone

* 'master' of https://github.com/keystonejs/keystone: (21 commits)
  Upgrade moment for CVE-2017-18214 (keystonejs#4592)
  replace knox git dependency with knox-s3 (keystonejs#4574)
  replace hardcode keystone to path admin variable (keystonejs#4586)
  Update Readme.md (keystonejs#4583)
  Update yo-generator.md (keystonejs#4581)
  Update application-updates.md (keystonejs#4582)
  Should check undefined instead, otherwise value === 0 will not be able to show (keystonejs#4524)
  Update README.md (keystonejs#4569)
  fix paginate to return on count error (keystonejs#4167)
  Deprecate currency setting (keystonejs#4132)
  Fix autocleanup for cloudinary fixes 3476 (keystonejs#4205)
  moved thumb check to field level
  (feat) implements image thumbnails for the File type
  Documentation about customizing the navigation bar
  Resetting the original initNav.js
  Replaced Array.isArray with _.isArray in initNav.js
  now nav sections can be simple objects, not necessarily array of objects as before
  fix external nav-link
  fixed bug in Accept-Language test that caused the test to fail
  Update dialog.js
  ...