Emulate SPI.setBitOrder(LSBFIRST) for LM4F and CC3200

As the peripherals only support MSB first, the SPI libraries for Tiva/Stellaris and CC3200 ignore the setBitOrder command. This pull request emulates support for LSB first using ARM instructions to reorder bits before and after transfer.

Also see http://forum.stellarisiti.com/topic/2089-spi-bit-order-on-tiva