Update simple plugin to use new API

It's still very simple, giving evidence that the new API isn't too
complicated.

kayleevc/plugins/simple.py

 heard, the plugin prints "Simple plugin says: [phrase]".
 """
 
-from .pluginbase import PluginBase
+from . import PluginBase, Handler
 
 
 class Plugin(PluginBase):
 
         self.corpus_strings.add(self.options['phrase'])
 
-    def confidence(self, text):
-        """Return 0 if text is not the phrase, 1 if it is"""
-        return 1 if text == self.options['phrase'] else 0
+    def get_handler(self, text):
+        """Return a handler if and only if the phrase is heard"""
+        if text == self.options['phrase']:
+            return SimpleHandler(1, text)
+        else:
+            return None
+
+
+class SimpleHandler(Handler):
+    """Handler for the simple plugin"""
 
-    def handle(self, text):
+    def __init__(self, confidence, text):
+        """Store the phrase that was heard"""
+        super().__init__(confidence)
+        self.text = text
+
+    def __call__(self, tts):
         """Print and speak the phrase"""
-        # Is there a matching command?
-        if self.confidence(text):
-            print("Simple plugin says:", text)
-            self.emit('tts', text)
-            return True
-        else:
-            return False
+        print("Simple plugin says:", self.text)
+        tts(self.text)