Add the ability to resolve JSON responses

This includes two functions one that can be used to resolve an error message in JSON and another to resolve a JSON response.

json_resolver.go

@@ -0,0 +1,23 @@
+package pastry
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// JSONResolver resolves JSON responses
+type JSONResolver struct{}
+
+// ResolveJSONError returns a default json error response
+func (resolver *JSONResolver) ResolveJSONError(w http.ResponseWriter, code int, message string) {
+	resolver.ResolveJSON(w, code, map[string]string{"error": message})
+}
+
+// ResolveJSON returns a json encoded response
+func (resolver *JSONResolver) ResolveJSON(w http.ResponseWriter, code int, payload interface{}) {
+	response, _ := json.Marshal(payload)
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(code)
+	w.Write(response)
+}