set noticeOnChannel to True by default (keep the same behaviour as eight)

With eight, by default the IRC status write line to channel. keep the same behaviour.
here my 2cents:

```
diff --git a/master/buildbot/status/irc.py b/master/buildbot/status/irc.py
index e1ddca8..5b0b22c 100644
--- a/master/buildbot/status/irc.py
+++ b/master/buildbot/status/irc.py
@@ -207,16 +207,21 @@ class IRC(base.StatusReceiverMultiService):
                  allowForce=False, tags=None, password=None, notify_events={},
                  showBlameList=True, useRevisions=False,
                  useSSL=False, lostDelay=None, failedDelay=None, useColors=True,
-                 allowShutdown=False, categories=None  # categories is deprecated
+                 allowShutdown=False, **kwargs
                  ):
         base.StatusReceiverMultiService.__init__(self)
 
+        deprecated_params = kwargs.keys()
+        print kwargs
+        if deprecated_params:
+            config.error("%s are deprecated" % (",".join(deprecated_params)))
```