Nuget issues

Update nuget packages to use WebActivatorEx

New functionality added in v1.8

• Updated primary ref binaries to MVC 5
• Convert Resource Chunks to JS - Previously, partials would not get converted to JS (they would rendered as spark templates inside of the rendered JS output).
• Fix stack-overflow exception - when parsing an empty shade file
• Adding implementation for PageInstrumentation in HttpContextWrapper - This fixes a NotImplementedException being thrown when trying to render a Razor page (via Html.Partial) from a Spark page. Razor expects PageInstrumentation to be implemented.