Allow set broadcast color with 3 digits like #444

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/models/broadcast_message.rb

@@ -20,8 +20,8 @@ class BroadcastMessage < ActiveRecord::Base
   validates :starts_at, presence: true
   validates :ends_at, presence: true
 
-  validates :color, format: { with: /\A\#[0-9A-Fa-f]{6}+\Z/ }, allow_blank: true
-  validates :font,  format: { with: /\A\#[0-9A-Fa-f]{6}+\Z/ }, allow_blank: true
+  validates :color, format: { with: /\A\#[0-9A-Fa-f]{3}{1,2}+\Z/ }, allow_blank: true
+  validates :font,  format: { with: /\A\#[0-9A-Fa-f]{3}{1,2}+\Z/ }, allow_blank: true
 
   def self.current
     where("ends_at > :now AND starts_at < :now", now: Time.zone.now).last