Refactoring ingots.

Method .except(:key) instead .merge(key: nil)
Refactoring session's tests

+ Add new method.
+ Delete sessions tested truly now.
Refactoring ingots

Replace users('valid'), users('no_admin') on users('admin') and
users('client'). Also for accounts.
Add test for owner and me
Refactoring

Ajax test move to their main test
Refactoring

Change method name
Refactoring: add new methods