Charts - Category Axis labels display in reverse order (regression)

fix #2533124

@davglass 
@ericf 
I discovered a regression in which category axis labels are displayed in reverse order. The unit test for was reversed to. It's a difficult issue to notice manually testing charts. I noticed the issue while working on new axis functionality.

This pull request contains the fix and an updated unit test. So far it has been fully tested on:
ie8, 9, 10 (both 10 browsers)
ff, chrome, safari, opera (latest on all)
android 2.x, 4.x
ios 6

Currently, the ms xp image is expired and a new one is unavailable. I will have to sort ie6, 7 testing tomorrow but I wanted to get the pull request in now.