Fixes #17246: Date custom fields can't store dates pre-1970. - part 2
Travis: only use Apache as web server

Workaround for build errors with PHP built-in web server since
30-Apr-2014 [1].

[1] https://github.com/travis-ci/travis-ci/issues/2235
Travis before_script add DB_TYPE

Since PHP >= 5.5 has deprecated mysql driver, we use mysqli instead
Travis before script: PORT was defined but not used