Windows does not support CHMOD, therefor we can not test not writable folders
Skip some more tests on Windows which just can not work at all
Fix single run of encryption tests and usages of uniqid() and fopen()
Correctly close handle of directory when listing certificates
Make it possible to cleanPath() absolute Windows paths
Mark files_trashbin/trashbin::testExpireOldFilesShared as incomplete on Windows

We can not test user1's filesystem anymore, because the StorageMapper
purges the Mapper table upon destroy(). Since we logged in a second user
the Mapper does not have the root entry `test-trashbin-user1/files_trashbin`
anymore. Therefor instead of `files-trashbin` it now tries to use `files_trashbin`
and therefor fails to strip the path correctly, so the file names are empty,
which later throws an error when trying to get the file extension.

This should be fixed, once owncloud/core#11233 is merged, since it makes the
Mapper recursive and generates any missing parents.