I've changed footer logo in odoo v9, Finally...!!!

Just create one xml file in /static/src/xml in your custom module & write this code..

<?xml version="1.0" encoding="UTF-8"?>

<templates id="template" xml:space="preserve">

<t t-extend="AppSwitcher" >

<t t-jquery=".o_application_switcher_footer" t-operation="replace">

<div class="o_application_switcher_footer">

<img src="/web_footer_logo/static/src/img/FP.jpg" alt="Odoo"/>

</div>

</t>

</t>

</templates>

Thanks & Regards,

Ayaz Mansuri