Added some configuration for PHP into phpunit.xml

[fabiang]

Renamed phpunit.xml to phpunti.xml.dist so everyone can overwrite it.

Also changed some config values for PHP when running unit tests:

• error_reporting (-1): makes sure every error is show, regardless of PHP version
• display_errors (on): show errors. Some people have this turned off
• log_errors (0): prevents errors to be logged twice
• memory_limit (-1): make sure PHPUnit can consume as much memory as needed. Some people have this set to weird values for CLI