Yajinja

- fix imports in python3

- sort files before interating over them
- don't error out on empty directories / directories without templates
- added `slugify_string` filter

- add b64enc and b64dec filters

- add `yaj` as an entrypoint
- raise exception if data being passed in is not a dict
- Friendly error messages when using incompatable flags

- allow passing a directory as an relative path
- allow passing template file as an relative path

- minor changes to packaging