Add extra_context parameter and apply override
Test extra_context override
Collapse ensure_dir_is_templated check
Refactor project template search
Apply *args hack to mercurial test for py3 test failure
Rm duplicate check, this already happens in cookiecutter.find.find_template
Merge pull request #2 from michaeljoseph/extra-context-api

Add extra_context parameter to `cookiecutter.main.cookiecutter` and `cookiecutter.generate.generate_context`