Update readme.md
Fixed some error handling bugs so that users will get exceptions for a few edge cases.  Fixed styled usage so it will choose default foreground and background colors based on environment (e.g. Powershell has a blue background).
Merge branch 'master' of https://github.com/adamabdelhamed/PowerArgs
Did a full public surface API pass so ensure all public APIs are documented.  I marked some previously public items as internal where appropriate.  That should not happen again.  There were also a few bug fixes, the most interesting was that enum values were being treated as case sensitive by default which should not have been the case.  I also added a new overload to the ArgValidator so that validators can choose to be run even if the user didn't specify the argument on the command line (useful for [ArgRequired] types of scenarios.
Added support for long form args.
Rev'd version and release notes