Meta: Upgrade Travis-CI to new infrastructure
Meta: Upgrade Travis-CI to new infrastructure

The new Travis CI container-based infrastructure is faster and more
powerful. The new infrastructure does not allows us to use sudo so need
to make certain changes accordingly.

Test plan:
$ ./precommit.sh

Ensure that builds pass on Travis with these set of changes.

Fixes #44

cs-shadow/phabricator-tools,kjedruczyk/phabricator-tools,kjedruczyk/phabricator-tools,bloomberg/phabricator-tools,bloomberg/phabricator-tools,cs-shadow/phabricator-tools,bloomberg/phabricator-tools,bloomberg/phabricator-tools,aevri/phabricator-tools,kjedruczyk/phabricator-tools,cs-shadow/phabricator-tools,aevri/phabricator-tools,kjedruczyk/phabricator-tools,aevri/phabricator-tools,aevri/phabricator-tools,kjedruczyk/phabricator-tools,cs-shadow/phabricator-tools,aevri/phabricator-tools,bloomberg/phabricator-tools,cs-shadow/phabricator-tools