Add method of accessing history dataset provenance.
Merge branch 'afgane_master'
galaxy: added first stub of oo interface
galaxy.objects: extended Workflow
galaxy.objects: more wrappers
added objects/galaxy_instance.py
galaxy objects: added delete_library and library test
galaxy objects: added delete_workflow
galaxy objects: create_library: added description and synopsis
galaxy objects: simplified error generation
galaxy objects: delete methods now have no return value
galaxy objects: more error checking
galaxy objects: added create/delete_history
galaxy objects: added upload_file_contents
galaxy objects: cleaned up error checking
galaxy objects: added more upload methods
galaxy objects: import workflow is now more flexible
galaxy objects: added dataset list to library instances
galaxy objects: added a dataset container base class
galaxy objects: refactored container and container dataset getters