* Use Contact User as Relay, Report, Subscribe.
* Use Account.representative to fetch contact user.
* Use find_local.
* No reason to use Account.representative in subscribe_service.
* Don't required representative!
* Fallback is included in Account.representative method.
Comparison was downcasing only one side, therefore if previously
existing account had a non-lowercase spelling, it would be ignored
when checking for duplicates.
New rake task `mastodon:maintenance:find_duplicate_usernames` will
help find constraint violations that might have occured from the
presence of this bug.
Bump version to 2.3.3
* Move specs for account finder methods to concern spec
* Move account finder methods to concern
* Improve spec wording
* Use more explicit comparison to ensure correct return value
* Add coverage for .find_local! and .find_remote!
* Add some methods to the finder
* Use arel on matching_username method
* Avoid ternary in matching domain method
* Simplify finder methods
* Use an AccountFinder class to simplify lookup
