Unnecessary reference

This creates a reference to a reference, clean it.

Fixes https://github.com/sdroege/gstreamer-rs/pull/48
Fixes https://github.com/sdroege/gstreamer-rs/issues/47

examples/src/bin/utils/mod.rs

@@ -30,7 +30,7 @@ impl fmt::Display for ExampleError {
             ExampleError::ElementError(ref element, ref err, ref debug) => {
                 write!(f, "Error from {}: {} ({:?})", element, err, debug)
             }
-            ExampleError::MissingFeature(ref feature) => write!(
+            ExampleError::MissingFeature(feature) => write!(
                 f,
                 "Feature {} is required. Please rebuild with --features {}",
                 feature,