add completed submitters verification method

app/models/completed_submitter.rb

@@ -4,16 +4,17 @@
 #
 # Table name: completed_submitters
 #
-#  id            :bigint           not null, primary key
-#  completed_at  :datetime         not null
-#  sms_count     :integer          not null
-#  source        :string           not null
-#  created_at    :datetime         not null
-#  updated_at    :datetime         not null
-#  account_id    :bigint           not null
-#  submission_id :bigint           not null
-#  submitter_id  :bigint           not null
-#  template_id   :bigint
+#  id                  :bigint           not null, primary key
+#  completed_at        :datetime         not null
+#  sms_count           :integer          not null
+#  source              :string           not null
+#  verification_method :string
+#  created_at          :datetime         not null
+#  updated_at          :datetime         not null
+#  account_id          :bigint           not null
+#  submission_id       :bigint           not null
+#  submitter_id        :bigint           not null
+#  template_id         :bigint
 #
 # Indexes
 #