callbacks: Only use dynamic.msg if it's not None in getCommandHelp
callbacks: Only use dynamic.msg if it's not None in getCommandHelp

Signed-off-by: James Vega <91ae71a1168cea0b65ac9975da69d5a7753116be@users.sourceforge.net>

mazaclub/mazabot-core,Ban3/Limnoria,prashantpawar/supybot-rothbot,buildbot/supybot,ProgVal/Limnoria-test,frumiousbandersnatch/supybot-code,haxwithaxe/supybot,jeffmahoney/supybot,Ban3/Limnoria,kblin/supybot-gsoc,mazaclub/mazabot-core,raboof/supybot,ProgVal/Limnoria-test