Big refactoring of registration

- Added datatable gem
- Addaed datatable to events, users (#422), registrations

app/views/conference_registrations/_questions.html.haml

@@ -0,0 +1,10 @@
+- @conference.questions.each do |q|
+  %h5
+    = "Q: #{q.title}"
+  - if q.question_type.id == 1  || q.question_type.id == 2 # yes/no or single choice
+    = f.input :qanswers, :collection => q.qanswers, :as => :select, :input_html => { :multiple => false }, :label => false, :include_blank => "Please make your choice",
+              :member_label => Proc.new {|a| a.answer.title}
+
+  - if q.question_type.id == 3  # multiple choice
+    = f.input :qanswers, :collection => q.qanswers, :as => :check_boxes, :label => false,
+              :member_label => Proc.new {|a| a.answer.title}