make-release: initial tarball test script

Initial tarball test script. It is currently testing tarball extraction,
$wgVersion and the commandline installer.

Prerequisites:

- A MediaWiki tarball in the folder you execute the script from
- SQLlite database
- Write permissions in the folder you execute the script from
- Phpunit installed and PHPUnit_* classes accessible by php

Usage:
  phpunit [switches] testReleaseTarball.php <version>

Change-Id: Iac86a255af436d46b7916e9b2b314a52b78e281b