Fix bounds check in CHAddr
Update net/ipv4 import with new paths.

Per
https://groups.google.com/forum/#!msg/golang-nuts/eD8dh3T9yyA/l5Ail-xfMiAJ
Merge pull request #5 from baptr/chaddr

Fix bounds check in CHAddr
Merge pull request #4 from baptr/import

Update net/ipv4 import with new paths.
Removed API warning.  API is stable.