Fixed the nuspec task to the latest style/standard.

 * double quotes, method parens, and good "this if that" postfix operators
 * removing all backwards compatible properties, we're breaking all the rules for 1.0!
 * setting up pretty formatting and require license as bool methods
 * use the push operator << and ternary set instead of if/then
 * authors, owners, and tags are arrays... let this helper set the join
 * the working dir separate from output file is unnecessary
how did nugetpack work trying to use instance properties as locals?
another nuget task that was incorrectly referencing instance props as locals
NuGet publish/push updates...

There is no publish command and there's no documentation on pushing without
publishing, it certainly isn't -CreateOnly, there's no such switch.
another nuget task with bad instance/local property refs