Give installed modules ability to have nav icons

Currently if you install a module there's not the associated class within the css to provide a nav icon for it (core modules get the clean sexy icons only). The main module layout handles this fine and pulls from the module assets. We're just going to make the navbar title grab an icon from the assets for aftermarket modules as well.

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<div style="text-align:center">
<b>Before This Patch</b>
<br>
![alt text](http://i.imgur.com/Mky91P1.png "Where are mah iconz!?")
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<hr>
<div style="text-align:center">
<b>After This Patch</b>
<br>
![alt text](http://i.imgur.com/hITHNi6.png "Zomg iconzes!")
</div>
<hr>

Furthermore, as I'm a big fan of the sexy greyscale color theme I almost went there.... What I mean is that if you want to, just toss this in what is now line 75 after the width declaration....

```style="filter: grayscale(100%); -webkit-filter: grayscale(100%); -moz-filter: grayscale(100%); -ms-filter: grayscale(100%); -o-filter: grayscale(100%); filter: gray;"```

and you'll get this...
<hr>
<div style="text-align:center">
<b>Greyscale</b>
<br>
![alt text](http://i.imgur.com/zkW9iqc.png "Where are mah iconz!?")
</div>
<hr>
I didn't include this because it's not really theme friendly as the rest of the icons you'd be able to control easily (from the accessible css file) but these you'd have to bust out nasty ```!important``` declarations over all of em. Again, just my train of thought for others, I'll personally mod it to greyscale myself as I dig the default design.

Before this update
(http://i.imgur.com/Mky91P1.png "Where are mah iconz!?")

After this update
(http://i.imgur.com/hITHNi6.png "Zomg iconzes!")

Furthermore, as I'm a big fan of the sexy greyscale color theme I almost went there.... What I mean is that if you want to, just toss this in what is now line 75...
```style="filter: grayscale(100%); -webkit-filter: grayscale(100%); -moz-filter: grayscale(100%); -ms-filter: grayscale(100%); -o-filter: grayscale(100%); filter: gray;"```
Which produces...
(http://i.imgur.com/zkW9iqc.png "Where are mah iconz!?")
and you'll get this, greyscale sexy icons! I didn't include this because it's not theme friendly as the rest of the icons you'd be able to control easily but these you'd have to bust out nasty ```!important``` declarations over all of em. Again, just my train of thought for others, I'll personally mod it to greyscale myself as I dig the default design.