Introduce a new config struct the lives above the raw disk implementation.

This should let us include values that would not be written to disk like the folder containing the config.

src/config/raw.rs

@@ -0,0 +1,20 @@
+use serde::Deserialize;
+use serde::Serialize;
+
+/// This is the struct for the writer.toml config file that ends up in each site's root directory.
+#[derive(Deserialize, Serialize)]
+pub(crate) struct RawConfig {
+    site_title: String,
+    author: Option<String>,
+    email: Option<String>,
+}
+
+impl Default for RawConfig {
+    fn default() -> Self {
+        RawConfig {
+            site_title: "My super awesome website".to_owned(),
+            author: None,
+            email: None,
+        }
+    }
+}