cc3000/cli: add crude dhcp command interface
cc3000/cli: add crude dhcp command interface

Two features: in the normal mode (parameter default 0), it wipes out any
static IP configuration setting up for DHCP.  Alternatively, with a
non-zero parameter it stores the current IP configuration as a static
configuration.

There's something wonky about DNS, though: sometimes it seems to get
stuck with the setting from a previous session.

pabigot/bsp430,pabigot/bsp430,pabigot/bsp430,pabigot/bsp430