Unable to import 1.9.0 databases

[Raoul Snyman]

The OpenLP 2.0 importer doesn't handle version 1.9.0 databases, where we didn't have XML in the verses just yet. I have a 1.9.0 database if you are looking for a test database.

An example traceback:

    Traceback (most recent call last):
      File "/usr/lib/pymodules/python2.6/openlp/core/ui/wizard.py", line 160, in onCurrentIdChanged
        self.performWizard()
      File "/usr/lib/pymodules/python2.6/openlp/plugins/songs/forms/songimportform.py", line 736, in performWizard
        if importer.do_import():
      File "/usr/lib/pymodules/python2.6/openlp/plugins/songs/lib/olpimport.py", line 214, in do_import
        clean_song(self.manager, new_song)
      File "/usr/lib/pymodules/python2.6/openlp/plugins/songs/lib/__init__.py", line 271, in clean_song
        verses = SongXML().get_verses(song.lyrics)
      File "/usr/lib/pymodules/python2.6/openlp/plugins/songs/lib/xml.py", line 141, in get_verses
        xml_iter = self.song_xml.getiterator()
    AttributeError: 'NoneType' object has no attribute 'getiterator'