A few minor housekeeping bits

including making the file executable, removing trailing whitespace,
using semver for the version number, and making the help/usage output a
bit more standard (IMHO).
Adding bits to usage output about -h/--help and -v/--version

as well as explicitly stringifying $version (it was printing a trailing
'%' for me).
Merge pull request #3 from meatballhat/usage-text-and-trailing-whitespace-brushup

Usage text and trailing whitespace brushup