standardize and clean up tests

[bshaffer]

No description provided.

[tmatsuo]

Can you summarize 1) changes and 2) how did you make those changes ? Should I really review all the 98 files?

[bshaffer]

@tmatsuo thanks! yes, good idea.

1. Rename every phpunit.xml file to phpunit.xml.dist.
2. Add Google copyright header to every phpunit.xml.dist.
3. Indent every phpunit.xml.dist file to 4 spaces
4. Add <testsuite name="..."> to every phpunit.xml.dist
5. If test/bootstrap.php was only including vendor/autoload.php, remove test/bootstrap.php and specify vendor/autoload.php as the bootstrap file in phpunit.xml.dist (see Remove unnecessary test/bootstrap.php files #373)