Fixed ajax requests for cases when store is installed into a subfolder

Hello guys. Recently, we have faced with a small trouble. 
When Magento is installed into a subfolder, for example http://yoursite.com/store/, AJAX requests initialised in newrelic.js file are not working since their urls are hardcoded to the domain root. Here is a small fix which gets store base url and make urls for AJAX requests depends on the base url.