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.
Remove uses of the is_active flag. Keep column in database (for now).
The only purpose of this flag was to filter out pools from the pool list
in the Add to Pool dialog. This hasn't had much use since autocomplete
was added. Most pools didn't set the flag correctly anyway.
