<openerp>
    <data>
        <template id="show_sign_in" inherit_id="website.show_sign_in">
            <!-- logging in from frontend should redirect back to frontend -->
            <a t-attf-href="/web/login" position="attributes">
                <attribute name="t-attf-href">/web/login?redirect=/</attribute>
            </a>
        </template>

        <template id="user_navbar" inherit_id="website.user_navbar">
            <!-- Remove the "mobile preview" icon -->
            <xpath expr="//li[a[@data-action='show-mobile-preview']]" position="replace"/>

            <!-- Remove the Help menu -->
            <xpath expr="//li[a[@id='help-menu-button']]" position="replace"/>

            <!-- Change the menu item's caption -->
            <xpath expr="//ul[@class='dropdown-menu js_usermenu']/li/a[@href='/web']" position="replace">
                <a href="/web" role="menuitem">Przejdź do aplikacji</a>
            </xpath>
        </template>


    </data>
</openerp>

<openerp>
    <data>
        <template id="website.show_sign_in" inherit_id="website.layout">
            <!-- logging in from frontend should redirect back to frontend -->
            <xpath expr="//ul[@id='top_menu']" position="inside">
                <li class="divider" groups="base.group_public"/>
                <li groups="base.group_public">
                    <a t-attf-href="/web/login?redirect=/">
                        <b>Sign in</b>
                    </a>
                </li>
            </xpath>
        </template>

        <template id="user_navbar" inherit_id="website.user_navbar">
            <!-- Remove the "mobile preview" icon -->
            <xpath expr="//li[a[@data-action='show-mobile-preview']]" position="replace"/>

            <!-- Remove the Help menu -->
            <xpath expr="//li[a[@id='help-menu-button']]" position="replace"/>

            <!-- Change the menu item's caption -->
            <xpath expr="//ul[@class='dropdown-menu js_usermenu']/li/a[@href='/web']" position="replace">
                <a href="/web" role="menuitem">Przejdź do aplikacji</a>
            </xpath>
        </template>


    </data>
</openerp>

Adjust to the most recent version of Odoo 8
Adjust to the most recent version of Odoo 8
