* Move the source normalization logic out of the post model
and into individual sources' strategies.
* Rewrite normalization tests to be handled into each source's test,
and expand them significantly. Previously we were only testing
a very small subset of domains and variants.
* Fix up normalization for several sites.
* Normalize fav.me urls into normal deviantart urls.
* Normalize spaces to underscores when saving other names. Preserve case
since case can be significant.
* Fix WikiPage#other_names_include to search case-insensitively (note:
this prevents using the index).
* Fix sources to return the raw tags in `#tags` and the normalized tags
in `#normalized_tags`. The normalized tags are the tags that will be
matched against other names.
* Don't fail on urls that don't contain the project id (direct image urls).
* Don't fail when the work is deleted.
* Parse artist name from url when possible. This way the artist finder works on bad_artstation_id posts.
* Set canonical source url to `https://artist.artstation.com/projects/12345` instead of
`https://www.artstation.com/artwork/1235` (this way we preserve the artist name).
* Cache api call.
* Include api call results in /source.json.
