Made the exceptions raised give more useful messages.
Made the exceptions raised give more useful messages.

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