It's faster than standard (hypervisor-based) one, so we will benefit
from it, especially when we want larger build matrix.
I thought we can't use it since it restricts the use of ``sudo``.
However, Travis provides ``addon`` feature to install additional
packages from container-based infrastructure.
References:
http://docs.travis-ci.com/user/workers/container-based-infrastructure/http://docs.travis-ci.com/user/apt/
Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
OGINO Masanori