Add output method to every hook file which merges stdout and stderr
Add STDERR and STDOUT description to file hook output
Hoke file output rather returns empty string than nil
Update changes, spec, version 3.1.9
Merge pull request #160 from vmoravec/hook-output-method

Add output method to hook file (merge stdout and stderr into a single line)
GetEthTypeFromSysfs returns correct type name for bridge device.

The path was provided by Waldemar Spitz <wspitz@uni-bonn.de>
Updated changelog