Sound Notifications

Hey there!
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Hello, I have to say that I am so happy to send this pull request. This is the first time I contribute to a GitHub project by adding a new feature. I am used to doing non-significant stuff and such.

This PR implements sound notifications to the client. Komanda does have notifications for OS X however they don't seem to work on when the app is built. I asked some people if it was a good idea to add sounds and it seems like it is.

**Sound Settings**
The sounds can be toggled. I know that most people like to just chill on channels and they don't want to be bugged all the time, so a sounds tab on the settings panel will let you turn off some or all sounds.

![screen shot 2014-06-25 at 4 07 09 am](https://cloud.githubusercontent.com/assets/4448627/3383271/1fa678c4-fc48-11e3-87f2-162424eea5c6.png)
*A screenshot of the sound settings on their default values*

**Testing**
I develop using an OS X machine running Mavericks. This feature should be compatible with any platform supported by node-webkit but do let me know if it doesn't work for you. The client and the sounds work perfectly while using ~~the grunt run task or using~~ the built standalone.

Cheers!

Developers...
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Adding sounds is dead easy. Let me give you a quick walkthrough of how to do so.

1.- Your sound files should be in `.ogg ` format and should go inside the `app/sounds` folder. Remember its file name.

2.- Go into `main.js` Line #137. This is the function that will add all the sounds into the ionSound plugin. Put the name of your file **WITHOUT** the extension in the sounds array. Followed by a colon and the volume level as a single decimal number. from 1.0 (max) all the way down to 0.0 (min).
![screen shot 2014-06-25 at 4 17 37 am](https://cloud.githubusercontent.com/assets/4448627/3383395/a2291918-fc49-11e3-8d6b-d98333769dc9.png)
*This is how the object looks like as of today Jun 25, 2014*

3.- Now to play any sound just run the following:

    $.ionSound.play("sound_name");
    
"sound_name" should be on the sound array I showed you above. That is pretty much it.

4.- (NOTE) - I added a listener to `main.js` called `"komanda:soundnotification"`. I run this event when messages are sent and here I check if they have that sound enabled to play it or not. This function should be self-explainable.

**Special thanks**
To everyone on the Komanda IRC channel that helped me get RequireJS working. Including the library was somewhat painful. At least I now know how to do it on future contributions.

ionDen's plugin: Ion.Sound
Project can be viewed here: https://github.com/IonDen/ion.sound
Licensed under: **MIT**
The library was modified a little bit so that it would use only ogg files so that it would work with node-webkit.