Replaced old spinner image.

**old**
![old](https://cloud.githubusercontent.com/assets/157533/2888092/ed005ca6-d504-11e3-8e9a-a8c06f2e9f9f.png)

**new**
![new](https://cloud.githubusercontent.com/assets/157533/2888093/ed02e2a0-d504-11e3-8e88-a37ca662a81e.png)

The new spinner is a bit smaller and lighter.
@maethu what do you think?