Bump database_cleaner to 1.6.1
Bump database_cleaner to 1.6.1

Bumps [database_cleaner](https://github.com/DatabaseCleaner/database_cleaner) from 1.5.3 to 1.6.1.
- [Changelog](https://github.com/DatabaseCleaner/database_cleaner/blob/master/History.rdoc)
- [Commits](https://github.com/DatabaseCleaner/database_cleaner/compare/v1.5.3...v1.6.1)
theodi/csvlint,theodi/csvlint,theodi/csvlint