Windows: If no color flag is already set

... then do not print a warning message
https://github.com/bootandy/dust/issues/87

src/main.rs

@@ -20,6 +20,10 @@ static DEFAULT_NUMBER_OF_LINES: usize = 30;
 
 #[cfg(windows)]
 fn init_color(no_color: bool) -> bool {
+    // If no color is already set do not print a warning message
+    if no_color {
+        true
+    } else {
         // Required for windows 10
         // Fails to resolve for windows 8 so disable color
         match ansi_term::enable_ansi_support() {
@@ -32,6 +36,7 @@ fn init_color(no_color: bool) -> bool {
             }
         }
     }
+}
 
 #[cfg(not(windows))]
 fn init_color(no_color: bool) -> bool {