Add memory tracking panel

[robhudson]

Similar to [Dowser](http://www.aminus.net/browser/dowser), look at implementing a memory tracking panel.

[munhitsu]

I've just ported the Dowser as standalone app for django. This may be handy for some: http://code.google.com/p/django-dowser/

[aaugustin]

Given that this ticket has stayed open for 5 years without any actual implementation efforts, I'm going to close it...

If someone will implements it as a third-party panel, and it works well, we can adopt it...