Add surveys; custom generated by admins

Available during registration or after conference

Co-authored-by: Shyukri <shshyukriev@suse.com>
Co-authored-by: Henne <hvogel@opensuse.org>
Co-authored-by: Moises <mdeniz@suse.com>

db/migrate/20160628093634_create_survey_questions.rb

@@ -0,0 +1,13 @@
+class CreateSurveyQuestions < ActiveRecord::Migration
+  def change
+    create_table :survey_questions do |t|
+      t.references :survey
+      t.string :title
+      t.integer :kind, default: 0
+      t.integer :min_choices
+      t.integer :max_choices
+      t.text :possible_answers
+      t.boolean :mandatory, default: false
+    end
+  end
+end