godep: Update lumberjack to v2.

Signed-off-by: Blaž Hrastnik <blaz.hrast@gmail.com>
host: Logbuf uses ActiveState/tail for tailing the file.

Signed-off-by: Blaž Hrastnik <blaz.hrast@gmail.com>
all: Update Godeps.

Signed-off-by: Blaž Hrastnik <blaz.hrast@gmail.com>