Add depth first tests
Finished tests for graph traversal
Push current state for collaboration (non-working)
Modify tests for depth first according to current understanding of problem
Add working function for depth_first
Remove repeated expression; rename variables for clarity
Fix typos in breadth first tests
Implement breadth first function
Refactor tests for depth first and breadth first. Start refactor of other tests.  Comment out unused test for add edge
added .travis.yml file for CI testing
Pull implementations of depth-first and breadth first traversals
Merge remote-tracking branch 'origin/graph_traversal1' into graph_traversal
Merge pull request #11 from MikeDelaney/graph_traversal

Graph traversal