Introduces new RegistrationPeriod Object for Conference

#416

app/views/admin/registration_periods/_form.html.haml

@@ -0,0 +1,8 @@
+%h1 Registration Period
+.row
+  .col-md-8
+    = semantic_form_for(@registration_period, url: admin_conference_registration_period_path(@conference.short_title)) do |f|
+      = f.input :start_date, as: :string, input_html: { id: 'registration-period-start-datepicker', readonly: 'readonly'  }
+      = f.input :end_date, as: :string, input_html: { id: 'registration-period-end-datepicker', readonly: 'readonly'  }
+      = f.input :description, hint: markdown_hint('This will appear in the Tickets segment of the splash.'), input_html: { rows: 5, data: { provide: 'markdown-editable' } }
+      = f.submit 'Save Registration Period', class: 'btn btn-primary'

app/views/admin/registration_periods/show.html.haml

@@ -0,0 +1,27 @@
+%h1 Registration Period
+- if @registration_period
+  .row
+    .col-md-6
+      %dl.dl-horizontal
+        %dt
+          Start Date
+        %dd
+          = @registration_period.start_date
+        %dt
+          End Date
+        %dd
+          = @registration_period.end_date
+        %dt
+          Description
+        %dd
+          - if !@conference.registration_period.description.blank?
+            = markdown(@conference.registration_period.description)
+
+  - if can? :update, @registration_period
+    = link_to 'Edit', edit_admin_conference_registration_period_path, class: 'btn btn-primary'
+  - if can? :destroy, @registration_period
+    = link_to 'Delete', admin_conference_registration_period_path,
+                        method: :delete, data: { confirm: 'Are you sure?' }, class: 'btn btn-danger'
+- else
+  - if can? :create, @conference
+    = link_to 'New Registration Period', new_admin_conference_registration_period_path, class: 'btn btn-primary'