Fuzzy searching

[moore3071]

A big benefit that a lot of the proposed search engines for Crates.io have is fuzzy searching. This is possible with Postgres itself. Postgres allows fuzzy searching with a module called pg_trgm. This module uses trigrams to identify potential mispellings.

This would be a nice enhancement to the current search functionality, but I can't say how it would affect the performance or query time.

[sgrif]

Let's centralize discussion in #1270 as this seems closely related.