Replace deprecated deferred.error() with fail()

Ported from rails/jquery-rails#184.

Author: carlosantoniodasilva

src/rails.js

@@ -367,7 +367,7 @@
         if (handleRemote === false) {
           rails.enableElement(link);
         } else {
-          handleRemote.error( function() { rails.enableElement(link); } );
+          handleRemote.fail( function() { rails.enableElement(link); } );
         }
         return false;
 
@@ -389,7 +389,7 @@
       if (handleRemote === false) {
         rails.enableFormElement(button);
       } else {
-        handleRemote.error( function() { rails.enableFormElement(button); } );
+        handleRemote.fail( function() { rails.enableFormElement(button); } );
       }
       return false;
     });