Apply banner style to the new banners

Banner sections can be saved (one banner can appear in several sections)
If the hex color is changed in the textfield, the color of the color picker changes.

app/models/banner.rb

@@ -7,15 +7,13 @@ class Banner < ActiveRecord::Base
                     length: { minimum: 2 }
   validates :description, presence: true
   validates :target_url, presence: true
-  validates :style, presence: true
-  validates :image, presence: true
   validates :post_started_at, presence: true
   validates :post_ended_at, presence: true
 
   has_many :sections
+  has_many :web_sections, through: :sections
 
   scope :with_active,   -> { where("post_started_at <= ?", Time.current).where("post_ended_at >= ?", Time.current) }
 
   scope :with_inactive, -> { where("post_started_at > ? or post_ended_at < ?", Time.current, Time.current) }
-
 end

app/models/banner/section.rb

@@ -1,5 +1,4 @@
 class Banner::Section < ActiveRecord::Base
-  enum sections: { homepage: 0, debates: 1, proposals: 2, budgets: 3, more_info: 4 }
-
   belongs_to :banner
+  belongs_to :web_section
 end

app/models/web_section.rb

@@ -0,0 +1,4 @@
+class WebSection < ActiveRecord::Base
+  has_many :sections
+  has_many :banners, through: :sections
+end