Refactoring User Account about RBSChange/evolutions#70

* Refactoring User Account (Request and Creation)
* The account table has been moved from *change_user_account_request* to *rbs_user_account_request*, don't forget to **reset your database!**
* UI improvement, better error messages, add a confirm password field
* User settings deleted, be useless regarding to new improvement in CreateAccount block (it made all the stuff now)
* Add a Unit Test on Clean Account Table Job
* Group Ids backoffice selection is gone, at the moment, just put the new user in the "web" realm group
* See RBSChange/evolutions#70 for discussions