Mostly modernize Conduit logs

Summary:

• Add GC support to conduit logs.
• Add Query support to conduit logs.
• Record the actual user PHID.
• Show client name.
• Support querying by specific method, so I can link to this from a setup issue.

@wez, this migration may not be fast. It took about 8 seconds for me to migrate 800,000 rows in the conduit_methodcalllog table. This adds a GC which should keep the table at a more manageable size in the future.

You can safely delete all data older than 30 days from this table, although you should do it by id instead of dateCreated since there's no key on dateCreated until this patch.

Test Plan:

• Ran GC.
• Looked at log UI.
• Ran Conduit methods.

Reviewers: btrahan

Reviewed By: btrahan

CC: wez, aran

Differential Revision: https://secure.phabricator.com/D6332