Refactor tabs implementation (#3268)

* Refactor tabs implementation

* tidy head.html

* test jquery-ui tabs

* Initial tabs code refactor

* test liquid parsing

* test liquid stack

* move into tabs.html

* test jekyll tabs

* construct array

* test cleaner way

* add example content

* test split hack

* fix md

* add site.emptyArray

* set good defaults

* fix CSS

* cleanup li

* fix a href

* fix content tabs

* add space to default

* remove a href underline

* rename docs/tab-test.md to docs/tab-example.md

* fix skip toc check

* add assignees

* add comment to reference example

* add documentation to example

* escape md

* move demo to top, pretty it up

* add word

* tweak wording

_sass/_base.sass

@@ -1326,9 +1326,11 @@ $feature-box-div-margin-bottom: 40px
 		margin: 0px !important
 
 .ui-tabs .ui-tabs-panel
-	padding: 0px !important
 	border: 1px solid #ccc !important
 
+.ui-tabs-anchor
+	text-decoration: none !important
+
 // Talk to us
 #talkToUs
 	h3, h4