Closed Issue: [AttributeRouting]Parsing error when using paranthesis in the route template's default values [978]

For the following action:

Note: the default value is a guid enclosed { , } characters.
```
[HttpGet("ForGuids/v3/{id:guid={6A9B7F3B-ED68-4759-ABBA-959ED47EB326}}")]
public string ForGuids(Guid id)
{
return "ForGuids:" + id.ToString();
}
```

Following error is thrown during configuration:

_System.ArgumentException : There is an incomplete parameter in this path segment: '{id}}'. Check that each '{' character has a matching '}' character.
Parameter name: routeTemplate

at System.Web.Http.Routing.HttpRouteParser.Parse(String routeTemplate) in c:\WebstackRuntime\Runtime\src\System.Web.Http\Routing\HttpRouteParser.cs:line 102
at System.Web.Http.Routing.HttpRoute..ctor(String routeTemplate, HttpRouteValueDictionary defaults, HttpRouteValueDictionary constraints, HttpRouteValueDictionary dataTokens, HttpMessageHandler handler) in c:\WebstackRuntime\Runtime\src\System.Web.Http\Routing\HttpRoute.cs:line 68
at System.Web.Http.Routing.HttpRoute..ctor(String routeTemplate, HttpRouteValueDictionary defaults, HttpRouteValueDictionary constraints) in c:\WebstackRuntime\Runtime\src\System.Web.Http\Routing\HttpRoute.cs:line 49
at System.Web.Http.Routing.HttpRouteBuilder.BuildHttpRoute(HttpRouteValueDictionary defaults, HttpRouteValueDictionary constraints, String routeTemplate) in c:\WebstackRuntime\Runtime\src\System.Web.Http\Routing\HttpRouteBuilder.cs:line 111
at System.Web.Http.Routing.HttpRouteBuilder.BuildHttpRoute(String routeTemplate, IEnumerable`1 httpMethods, String controllerName, String actionName) in c:\WebstackRuntime\Runtime\src\System.Web.Http\Routing\HttpRouteBuilder.cs:line 99
at System.Web.Http.HttpConfigurationExtensions.CreateAttributeRoutes(HttpRouteBuilder routeBuilder, String controllerName, Collection`1 routePrefixes, IGrouping`2 actionGrouping) in c:\WebstackRuntime\Runtime\src\System.Web.Http\HttpConfigurationExtensions.cs:line 143
at System.Web.Http.HttpConfigurationExtensions.MapHttpAttributeRoutes(HttpConfiguration configuration, HttpRouteBuilder routeBuilder) in c:\WebstackRuntime\Runtime\src\System.Web.Http\HttpConfigurationExtensions.cs:line 90
at System.Web.Http.HttpConfigurationExtensions.MapHttpAttributeRoutes(HttpConfiguration configuration) in c:\WebstackRuntime\Runtime\src\System.Web.Http\HttpConfigurationExtensions.cs:line 59
at WebStack.QA.Tests.AttributeRouting.DefaultValuesTest.UpdateConfiguration(HttpConfiguration config) in c:\WebstackRuntime\QA\Func\src\MainTests\Tests\AttributeRouting\DefaultValuesTest.cs:line 35_
Comments: GUIDs are already supported in attribute routing and you can just leave out the curly braces from the GUID. We can certainly improve the parser, but it won't really change this scenario.