Allow regular button and button-grouped on navbar

Issue
-
Regular button and button-grouped on navbar was inherting styles from navbar tab buttons.

Test Case
-
Add regular button or button-grouped in `#navbar footer`, notice that the styles are not correct.

Test code to reproduce issue, change data-footer attribute to test different components in footer:
```
<div id="afui">
    <div id="content" style="">
        <div class="panel" title="Page 1" data-header="header1" data-footer="footer1"  id="page1"  selected="true">
            <br>
            <div class="button-grouped">
                <a class="button">Button 1</a>
                <a class="button">Button 2</a>
                <a class="button">Button 3</a>
            </div>              
        </div>
    </div>
    
    <header id="header1" style='text-align:center'>
        <div class="button-grouped">
            <a class="button">Button 1</a>
            <a class="button">Button 2</a>
            <a class="button">Button 3</a>
        </div>    
    </header>
    
    <footer id="footer1" style='text-align:center'>
        <a href="#" class="icon home">Home</a>
        <a href="#" class="icon user">User</a>
    </footer>
    
    <footer id="footer2" style='text-align:center'>
        <div class="button-grouped">
            <a class="button">Button 1</a>
            <a class="button">Button 2</a>
            <a class="button">Button 3</a>
        </div>        
    </footer> 
    
    <footer id="footer3" style='text-align:center'>
        <a class="button icon settings">Button 1</a>    
    </footer> 

</div>
```

Fix
-
Change the CSS styles from `#navbar a` to `#navbar>footer>a:not(.button)` so that style is only applied to tab buttons in navbar. Other buttons and button-grouped will get the actual style

all `.css`, `ui/appframework.ui.js`, `af.8tiles.js` - changed for this fix.

`af.8tiles.js` - also added condition to append `metroMenu` only if `sidemenu` exists.