Optimize call to condor_history.
Optimize call to condor_history.

Resolves #302. Contributed by Kevin Shieh, thanks!

mehdisadeghi/saga-python,luis-rr/saga-python,telamonian/saga-python,mehdisadeghi/saga-python,luis-rr/saga-python,luis-rr/saga-python,telamonian/saga-python