Added new field for User - a name. 

* Added new field for user - a name. 
* Refactored registering so the user has to input the name (beginning with a capital letter). 
* Moved the initials of the author to user. Also added a method called author to Question so we don't have to change all the views which display author (I'm displaying user.name as author now). 
* Edited forms so the Author cannot be input now. And most of all refactored tests (added test for User which now checks most of validations on author which was tested in Question before).
You can add `counter_cache` to `User` (you can read more about counter cache here: http://guides.rubyonrails.org/association_basics.html#counter-cache). Counter cache (as the name says :)) is used to cache the number of associated objects (so you don't have to `COUNT(*)` in SQL each time you need this information).

```` ruby
    add_column :users, :answers_count, :integer, null: false, default: 0
````

...then add this option to the association in the model:

```` ruby
class Answer < ActiveRecord::Base
  belongs_to :user, counter_cache: true
  belongs_to :question, counter_cache: true

  ...
end
````