gem ffi 1.9.21 known issue building on ubuntu 16.04 and others

[WhiskeyTuesday]

See here and here for reference.

the ffi gem which is somewhere in the dependency tree is broken at this version. I don't know which dependency tree it's in or how to find out, but the version of something which hopefully you guys control should probably be incremented.

[tysongach]

We just made this project a Middleman Project Template (see #40), and by doing that we no longer check in the Gemfile.lock into this repo. That should mean this issue is no longer relevant because the ffi gem is not a first-class dependency of this project, and the installing of all gem dependencies now happens when you run the Middleman CLI to start a new app with this template.