Fulltext recipe indexing

[barneyb]

Create a Postgres fulltext index for recipe search, but don't actually use it (yet). Several not-quite-orthogonal concerns:

1. create a tsvector (fulltext search document) of "recipe text" per recipe
2. index that column (w/ owner info)
3. ensure recipes' fulltext documents are kept current as recipes, ingredients, and labels change
4. remove a number of no-longer-used search codepaths
5. dodge H2's use in tests, where it can't cope with the Postgres-specific syntax
6. expose some stats about the index state

[barneyb]

Because of initial indexing time, this is going to roll out in two phases: building the index and using the index for search. So this guy's toast, in favor of two sequential PRs to com.