Added motor mix diagrams

![Preview](http://i.imgur.com/wnJx6Zx.png)

This requires the SVG images already in the dev branch here:https://github.com/multiwii/baseflight-configurator/tree/development/images/motor_order

I made the switch case separate from the model type string one. That allows for better grouping and less repeating of code. 

Each image gets its own class for any tweaks that need to be made.

Custom mix and others are currently a question mark and have a custom CSS style to position it better.
![Preview](http://i.imgur.com/kZaenJA.png)

Let me know what you think.