install a newer kernel from backports

Debian's default 3.2 kernel seems to include a few IPv6-related
bugs that, in some cases, make IPv6 forwarding performance
unacceptable.  The linux-image-3.14-0.bpo.2-amd64 package
from backports appears to fix all of those known issues.
upgrade bash to fix CVE-2014-6271
Merge pull request #96 from fzylogic/master

install a newer kernel from backports