The previous commit changed it so that `/pools?search[name_matches]`
does a full-text search. So for example, `search[name_matches]=smiling`
will now match pool names containing any of the words "smiling",
"smile", "smiles", or "smiled".
This commit adds a `/pools?search[name_contains]` param that does what
`name_matches` did before, and switches to it in search forms. So for
example, `search[name_contains]=smiling` will only match pool names
containing the exact substring "smiling".
This change is so that `<field>_matches` works consistently across the
site, and so that it's possible to search pool names by either an exact
substring match, or by a looser natural language match.
This is a minor breaking API change. API users can replace
`/pools?search[name_matches]` with `/pools?search[name_contains]` to get
the same behavior as before. The same applies to /favorite_groups.
29a4ca0818