IE7-8 trim bug fixed.

I did some tests Friday and I noticed that native 'trim' function is not supported in IE7-IE8. To fix the problem I used jquery 'trim' instead of the native 'trim'. 

I removed also the delete 'window.googletag' because the unit tests are failing in IE7-IE8.  If you're curious there is an article explaning why at this address: http://perfectionkills.com/understanding-delete/#misconceptions.