Tell getopt to parse POSIX compatible.
Tell getopt to parse POSIX compatible.

By setting the environmental variable POSIXLY_CORRECT, getopt behaves
strictly POSIX-compatible.  This fixes the incorrect getopt parsing
style that breaks git-flow in several flavours of Linux.

Many thanks to Thiana for figuring this one out.

This should fix issues #28 and #29.

dhilgarth/gitflow,oddnoc/gitflow,yonglehou/gitflow-1,JelteF/gitflow