This commit removes all support and all references to the Spark board and to the CC3000 wireless part.

Squashed commit of the following:

Author: Gregory Nutt <gnutt@nuttx.org>
    Fix a few remaining refereces to cc3000.

Author: Alan Carvalho de Assis <acassis@gmail.com>
    drivers/wireless/cc3000: emove the driver to support CC3000 because it doesn't use the USRSOCKET

Author: Alan Carvalho de Assis <acassis@gmail.com>
    configs:  Remove board support to CC3000 from all relevant configurations.

Author: Gregory Nutt <gnutt@nuttx.org>
    configs/spark:  Removes Spark board configuration.  Still available in the Obsoleted repository.  This is preparation for removal of CC3000 support by Alan Carvalho de Assis.  If there is no CC3000 support, then there is no purpose in supporting the Spark either.