Correct invalid table markup

- Add required <tr> within <thead>
  - Add implicit <tbody> after <thead>

app/views/admin/users/_event_registrations.html.haml

@@ -7,10 +7,11 @@
     .well
       %table.datatable#event_registrations
         %thead
-          %th ID
-          %th Conference
-          %th Title
-          %th Attended
+          %tr
+            %th ID
+            %th Conference
+            %th Title
+            %th Attended
         %tbody
           - @user.events_registrations.each do |event_registration|
             - event = event_registration.event

app/views/admin/users/_submissions.html.haml

@@ -6,13 +6,14 @@
     .well
       %table.datatable#submissions
         %thead
-          %th ID
-          %th Conference
-          %th Title
-          %th State
-          %th Type
-          %th Rating
-          %th Created At
+          %tr
+            %th ID
+            %th Conference
+            %th Title
+            %th State
+            %th Type
+            %th Rating
+            %th Created At
         %tbody
           - @user.events.each do |event|
             %tr

app/views/admin/users/index.html.haml

@@ -12,13 +12,14 @@
   .col-md-12.table-responsive
     %table.datatable#users{ data: { source: admin_users_path(format: :json) } }
       %thead
-        %th{ width: '0' } ID
-        %th{ width: '0' } Confirmed?
-        %th{ width: '0' } Email
-        %th{ width: '50%' } Name
-        %th{ width: '0' } Conferences Attended
-        %th{ width: '50%' } Roles
-        %th{ width: '0' } Actions
+        %tr
+          %th{ width: '0' } ID
+          %th{ width: '0' } Confirmed?
+          %th{ width: '0' } Email
+          %th{ width: '50%' } Name
+          %th{ width: '0' } Conferences Attended
+          %th{ width: '50%' } Roles
+          %th{ width: '0' } Actions
       %tbody
 
 :javascript