Import export.lib.php to make unit tests friendlier to running independently

The HHVM test runner runs the unit tests in parallel. Currently some tests
fail because not all the dependencies are properly included.

This is similar to 1d58392622592d9a2cd6b64b797017d5ba95a113

Signed-off-by: Jeff Chan <jefftchan@gmail.com>
Merge pull request #1034 from jeffchan/fix-export-tests

Import export.lib.php to make unit tests friendlier to running independently