Initial implementation of custom Renderable trait.

src/bin.rs

@@ -3,6 +3,7 @@ extern crate nom;
 use renderer::compile_template;
 use renderer::CompiledTemplate;
 use renderer::DustRenderer;
+use renderer::Renderable;
 use std::env;
 use std::fs;
 use std::io::{self, Read};
@@ -65,3 +66,9 @@ fn read_context_from_stdin() -> serde_json::map::Map<String, serde_json::Value>
         _ => panic!("Expected context to be an object"),
     }
 }
+
+impl Renderable for serde_json::Value {
+    fn render(&self) -> String {
+        self.to_string()
+    }
+}