Adds re-architected Bluetooth UART driver from the Intel/Zephyr...

Adds re-architected Bluetooth UART driver from the Intel/Zephyr arduino101_firmware_source-v1.tar package.

Squashed commit of the following:

    drivers/bluetooth:  Re-architect Bluetooth UART driver to follow upper/lower half model.  Completely untested.
    drivers/bluetooth:  Grr..  Another band-aid commit to stay in sync with master.  Why is this so difficult
    drivers/bluetooth:  Band-aid commit to stay in sync with master.  Lost it somehow.
    drivers/wireless/bluetooth:  A few changes, mostly thought experiments.
    drivers/wireless/bluetooth:  UART-based Bluetooth driver ported from the Intel/Zephyr arduino101_firmware_source-v1.tar package.  This initial commit is the original files in the NuttX build environment with changes to conform with the coding standard.  It should not even build.