Make unit tests run on command line, phpunit 3.7 compatibility

The patches do the following:

- make the unit tests not crash with phpunit 3.7
- give us code coverage
- make it possible to use the cli version of phpunit: `./typo3/cli_dispatch.phpsh phpunit -c typo3conf/ext/caretaker_instance/tests/phpunit.xml --coverage-html typo3temp/cov typo3conf/ext/caretaker_instance/tests/`