make the versions and encryption app aware of the copy operation

Conflicts:
	apps/files_encryption/hooks/hooks.php
	apps/files_versions/appinfo/app.php
add unit test for rename and copy operation

Conflicts:
	apps/files_versions/appinfo/app.php
	apps/files_versions/tests/versions.php
make sure that we always find all versions
Merge pull request #11561 from owncloud/stable6-enc-webdavcopywithencryptionfix

[stable6] add support for webdav copy to the encryption and versions app