Bump psych from 2.1.0 to 2.2.4
Bump psych from 2.1.0 to 2.2.4

Bumps [psych](https://github.com/ruby/psych) from 2.1.0 to 2.2.4.
- [Changelog](https://github.com/ruby/psych/blob/master/CHANGELOG.rdoc)
- [Commits](https://github.com/ruby/psych/compare/v2.1.0...v2.2.4)
theodi/member-directory,theodi/member-directory,theodi/member-directory