social/social_media_tripadvisor/views/website_templates.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>

    <template id="footer_default_extra"
              inherit_id="website.footer_default">
      <xpath expr="//a[6]"
             position="after">

        <a t-att-href="website.social_tripadvisor"
           t-if="website.social_tripadvisor">
          <i class="fa fa-tripadvisor"/>
        </a>

      </xpath>
    </template>


    <!-- css and scripts -->
    <template id="assets_frontend"
              inherit_id="website.assets_frontend"
              name="Social Media Icon"
              priority="900">
      <xpath expr="."
             position="inside">

        <!-- version 4.4 of Fontawesome odoo uses only 4.0 -->
        <link rel="stylesheet"
              href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css"/>

      </xpath>
    </template>

  </data>
</openerp>