configs/flipnclick-sam3x: Using JTAG (vs. Bossac) I was finally able to load...

configs/flipnclick-sam3x:  Using JTAG (vs. Bossac) I was finally able to load code and verify the basic NSH configuration.  Updated READMEs.  Also switched to USART0 (vs UART0) for the serial console because I was not getting bi-directional communication on the VCOM.