enable testing individual tests

needed this to save time debugging oracle problems with sharing:

this PR allows you to test a single class like
```sh
$ ./autotest.sh oci Test_Share lib/share/share.php
```
@DeepDiver1975 @MTGap @kabum @IMM0rtalis partially fixes https://github.com/owncloud/core/issues/3851 (autotest.cmd adaptation is missing)