Add class to allow left-aligned text

Useful for row-level `th`
Scope scroll-depth to only `#maincontent`

Instead of using the entire page scroll depth, do some fancy math to determine scroll depth of `#maincontent`. This avoids potential data distrust caused when users don't scroll the entire footer, for example.
Remove baseline tracking, it distorts the averages.
Bumped dependency version number to 3.1.15
Merge branch 'release-3.1.15' into develop
Update analytics_scroll_depth.js
Merge pull request #447 from cmdprompt/patch-1

Update analytics_scroll_depth.js
Merge pull request #437 from smeranda/its-justified

Add a class to allow override of `th` text alignment.
Revert "Use correct CSS3 linear-gradient syntax."

This reverts commit 1e1b1556d8ec7ac989f4e65650741ffd48d2c3c2.
Use the correct W3C syntax for linear-gradients.
See #392.
Fix CSS validation for various properties
Remove opacity hacks that were supposed to fix Windows font rendering
These hacks had little success and the webkit-font-stroke made rendering
on Windows Chrome look horrible.
Merge branch 'develop' of github.com:unl/wdntemplates into develop
Bumped dependency version number to 3.1.16
Merge branch 'release-3.1.16' into develop
Remove unnecessary function.
Merge pull request #438 from smeranda/scroll-tweaks

Setup scroll-depth tracking to only focus on `#maincontent`
Destroy the unl_sso global cookie if the user's CAS session has ended
Merge pull request #468 from saltybeagle/destroy_unl_sso_cookie

Destroy the unl_sso global cookie if the user's CAS session has ended
Move the padding from the primary LI to the A