Added a tool to log messages by connecting a simple flash chip directly to the SPI of the autopilot

Added a new module for the logging using a memory directly plugged on SPI.

The documentation is available here : http://wiki.paparazziuav.org/wiki/Micro_logger
Also replace this macro with the respective function: `uart_transmit(&HS_LOG_UART, uart_read_buff[i]);
Same for other UART3 macros used later...