Fix few badges in README file and added coverage test with travis-ci.
Another minor fix with the badges.
Changed download badge on README.
Removed download badge from README.
Whitespace fixed to pass flake8 suggestions.
Addeed bag class and corresponding tests. Also modified stack, queue, bag to be iterators.
Minor typing fixes.
Changed python3.4 version to python3.3 for all tools.
Added api reference section in index.
Implemented union find class.
Whitespace and make docs for union find.
Added test for union find class.
Fix minor typing issue in union find test.
Added two more tests for union find.
Merge branch 'feature/unionfind' into develop
Expanded docstring for stack class.
Expanded on the documentation of the queue.
Added git flow commands to the contributing file.
Expanded documentation of the bag class.
Whitespace adjusted for few files.