Analytics app tracker update

[wongobongo]

The JavaScript in the analytics application uses the _gat._getTracker
method which is deprecated:

http://code.google.com/apis/analytics/docs/gaJS/gaJSApi_gat.html#_gat._getTracker

https://github.com/pinax/pinax/blob/master/pinax/apps/analytics/templatetags/analytics.py

I changed the code in my local copy of the app to use the newer
asynchronous queue. I'd be happy to push the change to github / add a
task to the pinax tracker.

http://code.google.com/apis/analytics/docs/tracking/asyncUsageGuide.html

The main benefit to this change is that you can avoid js exceptions
from not having the _gat object available due to any reason (like
users blocking Google Analytics / ad blockers). My IE7 was choking on
the missing _gat object and then not running the rest of my javascript
which then ruined my UI.

K