remove FubuMVC.Core.Assets from dependencies

No longer required and pulling this in causes all loads of exceptions

```
The configuration file is C:\Projects\Findly.FubuMVC\src\Findly.FubuMVC\web.config
Started service Fubu.Running.RemoteFubuMvcBootstrapper
Trying to start application C:\Projects\Findly.FubuMVC\src\Findly.FubuMVC with port number 5500
FubuMode = Development
System.AggregateException: One or more errors occurred. ---> System.TypeLoadException: Could not load type 'FubuMVC.Core.Registration.Diagnostics.Node
Event' from assembly 'FubuMVC.Core, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null'.
   at System.Reflection.RuntimeAssembly.GetExportedTypes(
RuntimeAssembly assembly, ObjectHandleOnStack retTypes)
   at System.Reflection.RuntimeAssembly.GetExportedTypes()
   at FubuMVC.Core.FubuExtensionF
```