Upgraded Gemfile from Rails 3.2.13 to Rails 4.0.0
Deleted the vendor/plugins directory, which Rails 4 no longer uses.
Included protected_attributes gem.

It should provide a smoother migration from Rails 3 to Rails 4. It will be eventually removed from the project and replaced by Rails 4 Strong Parameters.
Upgraded simple_forms gem from 1.4.1 to 3.0.0.rc

Currently a RC tag is being pulled from github. When 3.0.0 final is published to rubygems the Gemfile will probably remove the github reference; for now we have to use latest release candidate because of incompatibilities of older versions with Rails 4.
Pull simple_form 3.0.0.rc from rubygems instead of github.
Updated database_cleaner gem from 0.9.1 to 1.1.1
Adapted db/schema.rb to ruby 1.9 hash syntax.
Added new secret_key_base config parameter to initializers.

This is a new Rails4 config option that, if present, encripts the client-side cookie store to make it unreadable as well as tamper-proof.

It has been changed in the initializer file used for Travis CI, which is present in git, but also in the initializer files used in real environments, which are not in git.
Removed log4r gem because of incompatibilities with Rails 4.

This means going back to the default Rails logging.

The incompatibility is caused because Rails added a new "formatter" method that logging frameworks must implement. Log4r does not implement it; when trying to start a Rails 4 app using log4r logging, an "undefined method 'formatter'" error is raised and the startup fails. Highest criticality!

It seems logging frameworks (yell, log4r) have not adapted yet despite Rails 4 being released a month and half ago (and RCs long before that). There's a pull request in the log4r github repo supposedly fixing this that has received no attention for a month. I suppose people are happy enough with Rails logging, because obviously logging frameworks are not getting enough love. I'm really sorry, log4r is very nice, but I just can't hold migrating to Rails 4 because of this, and I've lost confidence in log4r devs adapting to the state of the art. Back to the default logger it is.
Removed version restriction for bootstrap-sass gem in Gemfile.

I'd like to be up to date, soon Bootstrap 3 will be released.
Moved flag images from vendor/assets/images to app/assets/images.

Rails 4 no longer precompiles image assets in the vendor/assets directory.
Run "rake rails:update" to update config files, then manually added back missiong options necessary for this app.

This ensures config files are up-to-date with Rails 4 defaults. Also the udpate removes the script directory and creates a new bin directory.