(GH-510) Fix: args for new fail with param=value

Some installers, MSIs in particular, specify silent arguments as
PROPERTY=value. Attempting to pass that in with
`choco new silentargs="/qn /norestart PROPERTY=value` will cause
choco to pass an empty string value in place of the passed arguments.

Fix the behavior to do the right thing when splitting the property
settings so that `=` can be passed as part of the arguments.

src/chocolatey/infrastructure.app/commands/ChocolateyNewCommand.cs

@@ -79,7 +79,7 @@ public void handle_additional_argument_parsing(IList<string> unparsedArguments,
 
             foreach (var unparsedArgument in unparsedArguments.or_empty_list_if_null())
             {
-                var property = unparsedArgument.Split(new[] {'='}, StringSplitOptions.RemoveEmptyEntries);
+                var property = unparsedArgument.Split(new[] { '=' }, 2, StringSplitOptions.RemoveEmptyEntries);
                 if (property.Count() == 2)
                 {
                     var propName = property[0].trim_safe();