Remove the user redefinition (cause compile error)

user is defined twice :
User user = userRepository.findOne(userDTO.getLogin());
User user = userService.createUserInformation(userDTO.getLogin(), [...]
The redefinition cause compile error on java 1.7
Merge pull request #834 from unknownboy/fix-for-java1.7

Remove the user redefinition (cause compile error)
Added javax.mail to logback
Corrected the error messages in the registration controller
The user PK is a technical ID, and not the login

Fix #807
Merge branch 'master' of github.com:jhipster/generator-jhipster