travis-ci: Add ppa:waja/precise-backports for fixed faketime

.travis.yml

@@ -8,6 +8,7 @@ before_install:
   - sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu/ trusty multiverse" && sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu/ trusty-updates multiverse"
   # /etc/hosts has IPv6 hosts (https://github.com/travis-ci/travis-ci/issues/4978)
   - sudo [ $(ip addr show | grep "inet6 ::1" | wc -l) -lt "1" ] && sudo sed -i '/^::1/d' /etc/hosts
+  - sudo add-apt-repository -y ppa:waja/trusty-backports
   - sudo apt-get update -qq
   - sudo apt-get purge -qq gawk
   # http://docs.travis-ci.com/user/trusty-ci-environment/ indicates, no MySQL on Trusty (yet)