eiru_sidebar_toggler/templates.xml

<openerp>
    <data>
      <template id="eiru_sidebar_toggler.assets" name="Eiru Sidebar Toggler" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <link rel="stylesheet" href="/eiru_sidebar_toggler/static/src/main.css" />
                 <script type="text/javascript" src="/eiru_sidebar_toggler/static/src/main.js" />
            </xpath>
        </template>
        <template id="eiru_sidebar_toggler.menu" name="Eiru Brand" inherit_id="web.menu">
            <xpath expr="//li[1]" position="before">
                <li class="eiru-sidebar-toggler eiru-sidebar-with-menu">
                    <i class="fa fa-bars"></i>
                </li>
            </xpath>
        </template>
    </data>
</openerp>