Change system requirement on PHP to 5.4+, #1078
Implement support for `$this` in closure
Suppress notice messages for undefined variables
Added translations for I18n\Validator component
Code cleaning
Code cleaning
Code cleaning for user password change
Code cleaning for user password change
To formulate username validator
Code cleaning for username
Code cleaning for username
Code cleaning for username and user name
Code cleaning for username and user name, email
Updated translations
Remove not used validators
Code cleaning for user custom
Translation updates
Cache flush upon user module install
Fixes translation for Chinese
Code cleaning up