added utils.executeex, which also returns output of stdout and stderr
update: read files in binary mode
mode binary mode optional (binary would require platform specific line endings to be converted which is not very portable, and mostly just text will do)
updated, using readfile now, remove obsolete os.remove commands
Merge pull request #67 from Tieske/add_executeex

added utils.executeex, which also returns output of stdout and stderr