Fixed couple typos
Replaced occurrences of separate MinLength/MaxLength rules with Length validation rule.
Corrected mistakes in last commit.
Committed changes to incorrect language keys in Group validation
Better consistency with symfony translations files.
Merge pull request #908 from empire/rename-translations-files

Translation: Better consistency with symfony translations files.
Removed trailing whitespaces
Merge pull request #901 from iainsaxon/deprecated-validation-rules

Removed deprecated MinLength/MaxLength validation rules
Updated the changelog
Refactored the Registration controller

The controller now handles the form itself and dispatches several events
during the workflow.
Added an event to allow modifying the default values of the user
Added an event before confirming the account
Added an event when logging the user in implicitly
Refactored the profile controller to use events
Refactored the password resetting submission
Refactored the ChangePasswordController to use events
Added a way to change the redirection url when sending the email
Refactored the FlashListener to keep it more DRY
Refactored the GroupController to use events
Moved the flash messages to the completed events