Remove TranslationStringFactory
Remove TranslationStringFactory

TranslationFacotry is only useful for non-plural forms. It only defines a
default domain for a particular string, and it's easily replacable with
a `setdefault`

https://github.com/Pylons/translationstring/blob/master/translationstring/__init__.py#L131

Issue #238

baditaflorin/osm-tasking-manager2,ethan-nelson/osm-tasking-manager2,stefanb/osm-tasking-manager2,baditaflorin/osm-tasking-manager2,jarmokivekas/osm-tasking-manager2,stefanb/osm-tasking-manager2,jarmokivekas/osm-tasking-manager2,KaiDalgleish/osm-tasking-manager2,KaiDalgleish/osm-tasking-manager2,ethan-nelson/osm-tasking-manager2,jarmokivekas/osm-tasking-manager2,KaiDalgleish/osm-tasking-manager2,jarmokivekas/osm-tasking-manager2,stefanb/osm-tasking-manager2,ethan-nelson/osm-tasking-manager2,KaiDalgleish/osm-tasking-manager2,baditaflorin/osm-tasking-manager2,stefanb/osm-tasking-manager2,ethan-nelson/osm-tasking-manager2,baditaflorin/osm-tasking-manager2