Merge pull request #5 from im-auld/binary

Implemented a binary heap class and associated tests.
Merge pull request #6 from im-auld/priorityq

Priorityq
Added graph structure from Eyuel's repo
PEP-8 fixes
Added node creation fixture
Added make_graph fixture
Added depth traversal test
Implemented depth first traversal, passes test
Depth traversal method actually does breadth traversal. MEthod and corresponding test have been renamed. oops.
Added depth traversal test
Implemented depth first traversal, passes test
Merge pull request #7 from im-auld/traverse

Traverse
Added travis config
Added requirements.txt for Travis
Update README.md
Solving merge conflicts
Modified graphy and testgraph to include weights for each edge. Changed our construction of neighbours to use dictionaries rather than lists.
Untracking .idea file.
Merge branch 'graph'