Updated command to 'tw' from 't'. Added Help

This patch changes the command name from 't' to 'tw' to
help with conflicts from other plugins.

Also added help

aprsd_twitter_plugin/twitter.py

@@ -10,13 +10,20 @@ LOG = logging.getLogger("APRSD")
 class SendTweetPlugin(plugin.APRSDRegexCommandPluginBase):
 
     version = "1.0"
-    # Look for any command that starts with w or W
-    command_regex = "^[tT]"
+    # Look for any command that starts with tw or tW or TW or Tw
+    command_regex = "^[tT][wW]"
     # the command is for ?
     command_name = "tweet"
 
     enabled = False
 
+    def help(self):
+        _help = [
+            "twitter: Send a Tweet!!",
+            "twitter: Format 'tw <message>'",
+        ]
+        return _help
+
     def setup(self):
         # Do some checks here?
         self.enabled = True