Creation of users' table
Adding libraries
Creation of users' model
Creation of the subscription system

Only subscription, not login
Modify management of adding SQL tables
Modify login controller
Modify login controller
Modify login error message
Modify login controller
Modify email library
Modify controller login
Remove useless getters
Modify login views
Modify login controller
Modify email library
Merge pull request #4 from Tatane58/master

Subscription system