Package search

[tchoutri]

Packages search with the https://lib.rs algorithm, and a drop-down for other sorting criteria.

https://github.com/rust-lang/rfcs/blob/master/text/1824-crates.io-default-ranking.md

Dependencies

• Fetch the download number for releases #348
• Induce a search penalty for deprecated packages #349

[jappeace]

I think this is a good option for the implementation: https://blog.crunchydata.com/blog/postgres-full-text-search-a-search-engine-in-a-database

[tchoutri]

@jappeace FTS is one thing but I think it's better for text documents. I'd rather start using trigrams first. :)