Create a plugin for up'ing a lo device

- Believe we need sudo to create netns
- Use syscall instead of relying on ip netns
- Add sudo to .travis.yml
- Needs more -E
- Revert Godeps GoVersion to 1.4.2
- in travis, test command is run with all necessary env vars
- Loopback plugin only works on 'lo' interface
- Update README, add loopback plugin config
- note script dependency on jq

Signed-off-by: Gabe Rosenhouse <grosenhouse@pivotal.io>

scripts/priv-net-run.sh

@@ -8,7 +8,6 @@ contid=$(printf '%x%x%x%x' $RANDOM $RANDOM $RANDOM $RANDOM)
 netnspath=/var/run/netns/$contid
 
 ip netns add $contid
-ip netns exec $contid ip link set lo up
 ./exec-plugins.sh add $contid $netnspath