Load Time Distribution Events sorting issue within Google Analytics report

[CLKeenan]

Currently, the load time events are passed through to GA as follows:

0-200ms
200-300ms
300-400ms
400-500ms
500-600ms
600-800ms
800-1000ms
1000-1200ms
1200-1500ms
1500-2000ms
2000ms above

Unfortunately, this means they are sorted like this in the GA sheet:

0-200ms
1000-1200ms
1200-1500ms
1500-2000ms
2000ms above
200-300ms
300-400ms
400-500ms
500-600ms
600-800ms
800-1000ms

This makes the Load Time Distribution chart difficult to read. I've fixed this within my own prebid.js file by adding a leading 0 to the 200-1000ms ranges, e.g. '0200-300ms'. It appears as though in the past the 1000ms+ ranges were entered as follows solving for this issue as well:

t2:1000-1200ms
t2:1200-1500ms
t2:1500-2000ms
t2:2000ms above

Certainly not urgent, but a relatively simple fix that I'm sure people who use the Google Analytics sheet would appreciate!

[protonate]

Sounds good to me, if you are able to submit a PR for this we can review.

[CLKeenan]

@protonate -- just created this PR: #510

Warning: this is my first PR ever, so apologies if I've created more confusion than efficiency.