Fix compat with 1.0.0

Closes #171

Author: alexcrichton

.travis.yml

@@ -1,5 +1,6 @@
 language: rust
 rust:
+  - 1.0.0
   - stable
   - beta
   - nightly

src/json.rs

@@ -331,12 +331,22 @@ pub enum DecoderError {
     EOF,
 }
 
-#[derive(Copy, PartialEq, Debug)]
+#[derive(Copy, Debug)]
 pub enum EncoderError {
     FmtError(fmt::Error),
     BadHashmapKey,
 }
 
+impl PartialEq for EncoderError {
+    fn eq(&self, other: &EncoderError) -> bool {
+        match (*self, *other) {
+            (EncoderError::FmtError(_), EncoderError::FmtError(_)) => true,
+            (EncoderError::BadHashmapKey, EncoderError::BadHashmapKey) => true,
+            _ => false,
+        }
+    }
+}
+
 impl Clone for EncoderError {
     fn clone(&self) -> Self { *self }
 }