Improve termimport logging

Improve the error logging in editor_Plugins_TermImport_Services_Import::handleFileSystemImport.

If mkdir throws an exception due a misconfigured path in filesystem.config, this no where pointed out in the logged error message. I got just "permission denied", which is correct at that point since apache user was not allowed to write the whole new path in /.

So please be more verbose in the case of an error and log at least the configured path btw. the path which should be created at that place.