refactor, add cli, add module pattern
Support GMT: prefix in addition to UTC:
Since the two are casually interchangeable, allow GMT to be used.
UTC is obviously preferred, but some systems require the older standard.
Added the npm install command
Add code fences for syntax highlighting
Add support to get the ISO-8601 numeric representation of the day of …
…the week when using "N".
Fix package name in readme, fixes #8.
Add format string W for ISO 8601 week of year