Skip the empty Set being emitted

This is unnecessary and unexpected so skipping it.

Author: benjchristensen

rxjava-contrib/rxjava-swing/src/main/java/rx/swing/sources/KeyEventSource.java

@@ -99,7 +99,7 @@ public Boolean call(KeyEvent event) {
             }
         });
 
-        return filteredKeyEvents.scan(Collections.<Integer>emptySet(), new CollectKeys());
+        return filteredKeyEvents.scan(Collections.<Integer>emptySet(), new CollectKeys()).skip(1);
     }
 
 }

rxjava-contrib/rxjava-swing/src/test/java/rx/swing/sources/KeyEventSourceTest.java

@@ -96,9 +96,6 @@ public void call() {
 
                 InOrder inOrder = inOrder(action);
                 fireKeyEvent(keyEvent(1, KeyEvent.KEY_PRESSED));
-                // we receive an empty event at the beginning due to behavior of scan with an initial value
-                inOrder.verify(action, times(1)).call(
-                        Collections.<Integer> emptySet());
                 inOrder.verify(action, times(1)).call(
                         new HashSet<Integer>(asList(1)));
                 verify(error, never()).call(Matchers.<Throwable> any());