http compressions stage 1 attempt 3

src/main.rs

@@ -240,11 +240,18 @@ impl Response {
 
     fn headers (&self) -> Vec<String> {
         match self {
-            Self::TextPlain(text, enc) => vec![
-                     f!("Content-Type: text/plain"),
-                format!("Content-Length: {}", text.len()),
-                enc.header().to_string(),
-            ],
+            Self::TextPlain(text, enc) => {
+                let mut v = vec![
+                    f!("Content-Type: text/plain"),
+                    format!("Content-Length: {}", text.len()),
+                ];
+
+                let enc = enc.header();
+
+                if !enc.is_empty() { v.push(enc.to_string()) }
+
+                v
+            },
             Self::OctetStream(bytes) => vec![
                      f!("Content-Type: application/octet-stream"),
                 format!("Content-Length: {}", bytes.len())