Add traditional circular wheel spinner

<img src="https://f.cloud.github.com/assets/19409/1848249/65bfbc46-7681-11e3-9655-2cb4f50bc57f.png" width="32">

Adds a traditional cog wheel spinner.  Generated from [this](https://gist.github.com/devongovett/5996869) Jade and Stylus which is a bit easier to read/more configurable due to Stylus's math, variable and looping abilities, and lack of prefixes. Happy to include that too if desired.

Thanks for the project, great resource!