Add #401.
Use new travis container infrastructure

Following instructions at http://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure/
Merge branch 'changelog-travis-container-no-sudo' into travis-container-no-sudo

Conflicts:
	CHANGELOG.md
Merge pull request #401 from jubianchi/travis-container-no-sudo

Use new travis container infrastructure