Fixed: can not install ruby_dep on Ruby 2.2.x
Fixed: can not install ruby_dep on Ruby 2.2.x

ruby_dep requiments ruby 2.2.5+
https://travis-ci.org/mitaku/komachi_heartbeat/jobs/154071808

sue445/komachi_heartbeat,mitaku/komachi_heartbeat,sue445/komachi_heartbeat,mitaku/komachi_heartbeat,mitaku/komachi_heartbeat,sue445/komachi_heartbeat