Updated experiment.js

Added helper function as documented her

 http:
//stackoverflow.com/questions/950087/how-to-include-a-javascript-file-in
-another-javascript-file
answer #47 by member - Kipras

updated function experiment()
used to load windowUnload on dom ready so any time you navigate off
page the experiment ends and submits data, which is not suitable for
interfaces with multiple pages, so added an if statment to check the
clicked href against an  array (soon to be) of pages which exclude the
windowUnload() when naviagting

updated submitExperimentData() to remove all code for constructing uri
for ajax request created new function experimentURI()

experimentURI() is now dry code, previously you had to update
experiment.js with your experiment url now it find the url string of
your site for you, to assist in submitExperimentData()
test pages