v0.16.1

• Prepare for 0.16.1 release - @sebjacobs
• Generate CHANGELOG file - @sebjacobs
• Build travis against jruby-9.1.9.0 - @sebjacobs
• Make Memoist.escape_punctuation compatible with MRI 2.7 - @byroot
• Remove ruby 1.9.2 from travis build matrix - @unasuke
• CHANGELOG - @matthewrudy
• travis: add ruby 2.6 - @matthewrudy
• add 2.5.1 to travis - @matthewrudy
• Remove ghit.me - @matthewrudy
• modify README.md - undefined