Use large text columns to store IP addresses

Summary: Fixes T10259. There was no real reason to do this ip2long() stuff in the first place -- it's very slightly smaller, but won't work with ipv6 and the savings are miniscule.

Test Plan:

• Ran migration.
• Viewed logs in web UI.
• Pulled and pushed.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10259

Differential Revision: https://secure.phabricator.com/D15165