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>
host: Lumberjack filename should be generated if empty.

Signed-off-by: Blaž Hrastnik <blaz.hrast@gmail.com>
test, host: Fix usage of Logbuf/Lumberjack.

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