PHPUnit now does a phar installation

This allows us to use the latest and greatest version of PHPUnit - currently we're on 4.0.17 - the limit now for pear. But this will put us on the latest travis version (4.0.19 as of present writing)

It also means we don't have to unnecessarily install DBUnit

See https://github.com/sebastianbergmann/phpunit/wiki/End-of-Life-for-PEAR-Installation-Method
and https://github.com/travis-ci/travis-ci/issues/2223#issuecomment-42401030