R1:f239d81c1cf8

Allow very long notes on flags

Summary: Fixes T4703. This is a VARCHAR(255) for no particular reason.

Test Plan: {F136160}

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T4703

Differential Revision: https://secure.phabricator.com/D8652