Update Ruby
Ruby 2.2.2 is getting close to end-of-life. This PR updates to ruby 2.4.2. Unfortunately it has to update tons of gems cause they don't work well with ruby 2.4.2. It also:
- updates Rails to 2.4.10
- fixes cucumber tests that were broken
- installs Travis as CI.
Merging #91 into master
in the conventional way.