Icon update

Hi, 
I had issue with the default icon: it was not really detailed, too flashy, and also used 3D letters. It was distracting to me and didn't blended well on my desktop.  So , here I propose a pull-request with a proposition , instead of just a local tweak on my install. The new icon keeps the RGB colors of the previous icon, and include them in a sort of camera lens.

 commit message *"Icon update; reamake of the *.svg scalable icon, and pause+recording variant, with export to all *.pg size. The icon now doesn't show big SSR letter nor too saturated colors. It fix a issue on desktop with rich icon theme ; the SSR icon was not looking too good on them. Credits goes also to the public domain work of mrallowski on openclipart.org for the base of the lens icon gfx."*

Result screenshot on my docker:
![2014-06-28_screenshot044458_net](https://cloud.githubusercontent.com/assets/4021867/3419591/99fc5918-fe6e-11e3-9e8b-bf33c097f3e9.jpg)

Feel free to merge or not, I know cosmetic change like this depends a lot on taste. 
Thx again for SimpleScreenRecorder.