Support Uglify's wrap and define features

[dylang]

Until mishoo/UglifyJS#33 is closed there are still some other options that would be helpful to support.

Wrap will wrap your code within a closure, helpful to make sure no functions are leaking into the global scope.

Define will define variables in the closure which provides an easy way to hardcode in the JS data like the the build date, version, and debug information.

[dylang]

Figured out that define is already supported, just not well documented.

                compress: {
                    drop_debugger: false,   // don't remove debugger;
                    warnings: false,        // don't show any warnings
                    global_defs: {
                        DEBUG: true
                    }
                }

Closing this because I have a pull request in for wrap support.