Fix broken encoded model in UserLookupOptimization migration.
Regenerate the UserLookupOptimization migration from scratch since it was broken.

Also renamed the AddMinRequrerdVersionColumn class to match its migration ID: AddMinRequiredVerison. Because anything else is confusing (plus a little paranoia about it causing problems further down the road especiall if we do any migration related code).
Merge pull request #988 from NuGet/tilovell-fix-userbyusername-migration

Fix broken encoded model in UserLookupOptimization migration.