ipv6: Add a somewhat modified version of the ipv6 stack from gigaboot.

This has been tweaked a little bit to fit within depthcharge, but the changes
were minimal. Some changes will come in the future which clean up the style to
match with depthcharge's, and also to smooth out the fairly ham fisted
integration with the other network infrastructure.

Change-Id: I51d75e294ddb9450a278576a0db1e6d4c0e27e13
6 files changed