technical implementation to display a progress bar for uploaded files

+ design missing
Merge branch 'develop' into feature/upload-progress

* develop: (28 commits)
  update changelog
  store author id and name on the blog post
  custom published at blog post attribute
  disable new blog post button when clicked
  update blog generator
  extends boy dom element with information about the current object
  use javascript user model to prefill new blog post
  javascript user model
  simplified user model
  bugfix: bootstrap red css alert class
  button to create new blog post in place
  blog post pagination
  blog pagination
  blog without cells dependency
  bugfix: got the 404 bugfix wrong and reverted the change accidentially
  update gems
  bugfix: 404 fix was not applied to generator
  update changelog
  update gems
  bugfix: in case no homepage found still display a 404 page
  ...
file upload progress bar

fixes #225
change the order in which to add new progress bars
Merge branch 'feature/upload-progress' into develop

* feature/upload-progress:
  change the order in which to add new progress bars
  file upload progress bar
  technical implementation to display a progress bar for uploaded files
bugfix: remove test disqus shortname