refactors letter and sms generation codes [#332]

app/models/verification/letter.rb

@@ -54,8 +54,10 @@ class Verification::Letter
       district:      address[:nombre_distrito] }
   end
 
-  def generate_verification_code
-    rand.to_s[2..7]
-  end
+  private
+
+    def generate_verification_code
+      rand.to_s[2..7]
+    end
 
 end

app/models/verification/sms.rb

@@ -24,7 +24,7 @@ class Verification::Sms
   end
 
   def update_user_phone_information
-    user.update(unconfirmed_phone: phone, sms_confirmation_code: four_digit_code)
+    user.update(unconfirmed_phone: phone, sms_confirmation_code: generate_confirmation_code)
   end
 
   def send_sms
@@ -41,7 +41,7 @@ class Verification::Sms
 
   private
 
-    def four_digit_code
+    def generate_confirmation_code
       rand.to_s[2..5]
     end
 end