Show EULA link and plagiarism pledge for assignment submissions.

Closes PLAT-3664

Test Plan:
- Install an LTI 2 tool that uses a EULA
- Create a single assignment with online upload AND text entry
  submission types
- Set the plagiarism pledge in the account settings
- As a student go to the assignment submission page
- Verify that the online upload tab shows a checkbox with a
  link to the EULA and the similarity pledge
- Verify the same for the text entry tab
- Verify the EULA link goes to the correct URL
- Verify the checkbox must be checked for both online upload and
  text entry before the submission can be submitted

Change-Id: Id35732c7b9a21883f1694857e72a857583522b63
Reviewed-on: https://gerrit.instructure.com/160417
Tested-by: Jenkins
Reviewed-by: Marc Alan Phillips <mphillips@instructure.com>
Reviewed-by: Han Ngo <hngo@instructure.com>
QA-Review: August Thornton <august@instructure.com>
Product-Review: Jesse Poulos <jpoulos@instructure.com>

app/views/assignments/_eula_checkbox.html.erb

@@ -26,9 +26,8 @@
           <% if eula_url.present? %>
             <%= t "I agree to the tool's" %>
             <%= raw("<a href='#{eula_url}'>#{t 'End-User License Agreement.'}</a>") %>
-          <% else %>
-            <%= @similarity_pledge %>
           <% end %>
+          <div><%= @similarity_pledge %></div>
         </label>
       </td>
     </tr>