wireless/bluetooth:  Adds most of the logic to get the Tx path working.  Still missing the logic to recover the Bluetooth connection structure given the destination address in the socket address.

    wireless/bluetooth:  This completes the basic logic path that gets frames from the Bluetooth stack and into the network layer.
    wireless/bluetooth:  Fleshes out some of the network packet receive logic.
    wireless/bluetooth:  Replace buffer allocated with primitive allocator from ieee 802.15.4.
    wireless/ieee802154:  Fix a few typos.
    wireless/bluetooth:  More renaming in preparation for some real work.
    wireless/bluetooth:  Some trivial renaming; update comments

This comment adds (1) basic support for AF_BLUETOOTH sockets.  The logic compiles but is still incomplete.  Support for Bluetooth is general is still dependent on CONFIG_EXPERMIMENTAL because it is not yet ready for used.

Squashed commit of the following:

    wireless/bluetooth:  Some small changes that gets to a clean compile by just eliminating some incorrect implementations (still with a lot of warnings.  The logic is still incomplete but now not so lethal.
    wireless/bluetooth:  Restructuring:  Connection interfaces should internal to wireless/bluetooth.  include/nuttx/wireless/bt_conn.h removed and merged with wireless/bluetooth/bt_conn.h.  Several fix to get closer to bt_netdev.c compiling.  Need to design some not interfaces and use some existing interfaces to send and receiv packets.
    wireless/bluetooth: Some organization with some network device compile errors fixed.  Still not even close to compiling.
    net/bluetooth:  Fix numerous compile issues; Still open design issues with regard to the interface with the Bluetooth stack.
    wireless/bluetooth:  Create bt_netdev.c with a crude copy of mac802154_netdev.c.  Does not not even compile yet.
    include/nuttx/net:  Add bluetooth.h.  Content is not yet correct.
    net/netpackets:  Add bluetooth.h.  Update net/bluetooth to use new socket address definition.
    net/bluetooth:  Some fixes for initial build.
    net/bluetooth:  Add initial support for Bluetooth sockets.  The initial cut is just the a clone of the IEEE 802.15.4 socket support with name changes.
    net/ieee802154:  Fix some typos noted when cloning to create net/bluetooth.

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.