Added a test for str(prov.QueriesNotInitedError)

Just because it was annoying me that it was pulling down coverage.
Added \#*\# to .gitignore

This is so that it doesn't try and deal with emacs backup files.
Added prov.fetch_associated_activities and related tests

This function returns all the activities associated with the given agent.
Added .\# to .gitignore

It turns out emacs has even more tempory file name conventions...
Added prov.fetch_entities_derived_by_activity(graph, activity) and tests

This function returns any entity in graph for which there is a qualified
derivation with the property hadActivity equal to activity.