Add validate format for user's name
Refactoring models
Add validate format for article's title
Refactoring unit test
Change limit for title column in articles and comments
Most databases (sqlite included, which is the default db in RoR) automatically index the primary key
Refactoring save alert's messages to controllers
Delete rescue RecordNotFound because 'production' server do it same
Refactoring functional test
User may already be found
Refactoring redirect