Handlebars Integration

Since there have been a few requests for Handlebars support, and due to Hogan's lack of Lambda support (unless adding in the compiler + uncompiled JST's), I decided that it was time to move from Hogan to Handlebars.

So far, this fork contains the following:
* Full integration of Handlebars with Jurassic
* Precompilation support (with support for helpers!)
* .NET 3.5+ support
* Basic Unit Tests

To use Handlebars, in your CassetteConfiguration file, add in the following:
```c#
public class HandlebarsConfiguration : IConfiguration<HandlebarsSettings>
    {
        public void Configure(HandlebarsSettings settings) {
            settings.JavaScriptVariableName = "JST";
            settings.KnownHelpers = new List<string> {"t", "eachkeys"};
        }
    }
```

Feel free to let me know if there are any bugs or things that I may have overlooked.