Both apps/dhcp/dhcp.c:dhcpc_configured() and cpu/6502/ipconfig/ipconfig.c:dhcpc_configured() presume the first parameter of uip_nameserver_update() to be const. As there's no reason for it to be not const just make it const.
On the same commit the src have been uncrustified and some typo fixes as well as includes missing.
Adds a common in contiki nameserver pool for handling name resolution servers. This will allow in following commit to use RDNSS messages within RA.
