added .gitignore
Initial attempt at using a persistent job history
Add job_history support for touch_files_only mode
History properly handles jobs with no inputs
Checksum pipeline function body and parameters; Fine grain control over checksum level
Partial fix History-aware @split decorator
Add travis-ci and tox
travis-ci depends on tox
Move history reset into master thread, multiple-output files handled properly
Allow inputs which aren't in history
add unittests for job completion checksum functions
Merge branch 'job_completion' of github.com:jakebiesinger/ruffus into job_completion