Summary:
- When a setup issue is nonfatal (i.e., a warning), instruct the user to edit the value from the web UI instead of using `bin/config`.
- When the user edits configuration in response to a setup issue, send them back to the issue when they're done.
- When an issue relates to PHP configuration, link to the PHP documentation on configuration.
- Add new-style setup check for timezone issues.
Test Plan: Mucked with my timezone config, resolved the issues I created.
Reviewers: codeblock, btrahan, vrana
Reviewed By: codeblock
CC: aran
Maniphest Tasks: T2221, T2228
Differential Revision: https://secure.phabricator.com/D4298
