修改bug<course主页-加入课程，建议修复“取消”按钮样式与“加入”保持一致>

Signed-off-by: alan <547533434@qq.com>

app/views/courses/_join_private_course.html.erb

@@ -62,8 +62,8 @@
               <input class=" width190" type="password" name="course_password" id="course_password" value="" >
             </li>
             <li>
-              <a href="#" class="btn" onclick="submit_form(this);"><%= l(:label_new_join)  %></a>
-              <a href="#" onclick="hideModal(this);"><%= l(:button_cancel)%></a>
+              <a href="#" class="btn" style="margin-left: 50px;" onclick="submit_form(this);"><%= l(:label_new_join)  %></a>
+              <a href="#" class="btn" style="margin-left: 20px;" onclick="hideModal(this);"><%= l(:button_cancel)%></a>
             </li>
           </ul>
       <% end%>