After saving a custom query, redirect to its results page

Summary:
Ref T2625. Currently, after saving a query the user is redirected to "/search/", which isn't especially useful. Instead, redirect them back into the application they came from and to the query results page.

Also, query hashes may contain ".", which does not match \w. Use [^/] instead.

Test Plan: Saved some custom queries.

Reviewers: btrahan, blc

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2625

Differential Revision: https://secure.phabricator.com/D6055