Added .travis.yml
Added .ruby-version for contributions
Added graph database scaffold and RSpec
Standard graph #relate, #in, #out methods
OpenStruct -> Edge class
Edges are immutable
Return nodes, not edges
Added specs for #in
Added code coverage with SimpleCov
Stop dependencies between tests with before(:all) hook
Remove ostruct require
Moved Graph, Node and Edge to their own files in app/services
Bundle caching and tweaked test command
Merge branch 'travis-ci'