netduino-2 board with stm32f2

Netduino 2 stm32f2 using CDC.  Mostly being a copy of the STM32F4DISCOVERY with STM F2 libraries and pin changes.  CAN portion is not tested yet thus excluded in the board config.  Pin assignment is attached. Edit: pin chart updated.

![netduino2elua](https://f.cloud.github.com/assets/1572460/978528/2138506e-06c0-11e3-9c2f-5110e8149610.png)