SQL Patch Management: SQL Changes

Summary:
Splits out the SQL changes. These are most of the changes, but primarily mechanical:

• Moved "initialize.sql" to "0000.legacy.sql" and partially reverted to an older version, such that patches 0000 + 000 + 001 + ... + 137 put us in the right state when applied sequentially.
• Removed "create database" commands from all SQL. These are handled by separate DB patches now, so we have the data to do operations like "storage databases" (list databases) and "storage destroy" (drop databases).
• Removed "phabricator_" namespace from all SQL, and replaced with "{$NAMESPACE}_" token so we can namespace databases.
• Shortened some column lengths so patches apply correctly if originally created as InnoDB; also a few similar tweaks elsewhere.

Test Plan: See D2323 for discussion and test plan.

Reviewers: edward, vrana, btrahan, jungejason

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T140, T345

Differential Revision: https://secure.phabricator.com/D2329