Feature: Twilio SMS Channel (#658)

Twilio SMS Channel
Fixes :  #350

db/migrate/20200330071706_create_channel_twilio_sms.rb

@@ -0,0 +1,11 @@
+class CreateChannelTwilioSms < ActiveRecord::Migration[6.0]
+  def change
+    create_table :channel_twilio_sms do |t|
+      t.string :phone_number, null: false
+      t.string :auth_token, null: false
+      t.string :account_sid, null: false
+      t.integer :account_id, null: false
+      t.timestamps
+    end
+  end
+end

db/migrate/20200404135009_add_unique_validation_index.rb

@@ -0,0 +1,7 @@
+class AddUniqueValidationIndex < ActiveRecord::Migration[6.0]
+  def change
+    add_index :channel_twitter_profiles, [:account_id, :profile_id], unique: true
+    add_index :channel_twilio_sms, [:account_id, :phone_number], unique: true
+    add_index :webhooks, [:account_id, :url], unique: true
+  end
+end