Increase conformance to Handler subclassing rules

According to documentation and existing functions:
    * _close should be close and call Handler close to properly
      unregister from existing handlers
    * emit should not re-filter logs, it is handled by the format
      function.
    * __init__ should not set a formatter, it is the responsability of
      the dev to do so. Old code forbid subclassing the formatter and
      using it.

Author: EvaSDK

fluent/handler.py

@@ -63,14 +63,16 @@ def __init__(self,
         self.sender = sender.FluentSender(tag,
                                           host=host, port=port,
                                           timeout=timeout, verbose=verbose)
-        self.fmt = FluentRecordFormatter()
         logging.Handler.__init__(self)
 
     def emit(self, record):
-        if record.levelno < self.level:
-            return
-        data = self.fmt.format(record)
+        data = self.format(record)
         self.sender.emit(None, data)
 
-    def _close(self):
-        self.sender._close()
+    def close(self):
+        self.acquire()
+        try:
+            self.sender._close()
+            logging.Handler.close(self)
+        finally:
+            self.release()

tests/test_handler.py

@@ -27,12 +27,13 @@ def test_simple(self):
 
         logging.basicConfig(level=logging.INFO)
         log = logging.getLogger('fluent.test')
+        handler.setFormatter(fluent.handler.FluentRecordFormatter())
         log.addHandler(handler)
         log.info({
             'from': 'userA',
             'to': 'userB'
         })
-        handler._close()
+        handler.close()
 
         data = self.get_data()
         eq = self.assertEqual