Could not load OpenSSL.
You must recompile Ruby with OpenSSL support or change the sources in your Gemfile from 'https' to 'http'.
Instructions for compiling with OpenSSL using RVM are available at rvm.io/packages/openssl.
Gemfileを以下のとおり変更。(https->http)
source 'https://rubygems.org' -> source 'http://rubygems.org'