Fix #26: Option parsing fails on RPi

getopt has an int return value
It seems I used an old/wrong man page, however http://linux.about.com/library/cmd/blcmdl3_popt.htm states that
poptGetNext returns an int instead of char. This solution has been tested on RPi.
Merge pull request #27 from penguineer/issue26

Fix #26: Option parsing fails on RPi