Things to do:
Get the time in micro-seconds using the function: microtime().
Turn the micro-time into an array using the explode()
Add the two parts to the array together (the micro-seconds to
Repeat steps 1,2 and 3 for the bottom of the page
Find the total loading time by taking the time taken at the
end of the page from the time taken at the top of the page
Round the microtime and return it to the browser