Allow custom options for stdout_stream and stderr_stream. Fixes #495
No need for special cases when converting stdout_stream options
NOTICE+=Steven Armstrong

Signed-off-by: Steven Armstrong <steven.armstrong@inf.ethz.ch>
Not converting every string of digits to ints anymore
Merge pull request #497 from asteven/notice

NOTICE+=Steven Armstrong
Merge pull request #496 from cezarsa/master

Allow custom options for stdout_stream and stderr_stream